From 4732b6033167bb7c3c3331d6975b5ed2ed5de8ef Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@gmail.com>
Date: Thu, 30 Jul 2026 09:38:26 -0300
Subject: [PATCH 1/5] refactor: move embedded runtime JS to real .js files
 compiled in via js2c

The ~26KB of JavaScript previously embedded as C++ string literals now
lives in NativeScript/runtime/js/*.js. A "Generate RuntimeBuiltins"
build phase runs tools/js2c.mjs to emit a generated source table, and
call sites go through BuiltinLoader::RunBuiltin, which sets proper
internal/<name>.js script origins and shares an in-process bytecode
cache across isolates so workers stop re-parsing the builtins.
---
 .gitignore                                  |   3 +
 NativeScript/runtime/BuiltinLoader.cpp      |  83 +++++++++++
 NativeScript/runtime/BuiltinLoader.h        |  23 +++
 NativeScript/runtime/ClassBuilder.mm        |  24 +---
 NativeScript/runtime/ErrorEvents.cpp        |  93 +-----------
 NativeScript/runtime/Events.cpp             | 141 +------------------
 NativeScript/runtime/Helpers.mm             |  35 +----
 NativeScript/runtime/InlineFunctions.cpp    | 129 +----------------
 NativeScript/runtime/ModuleInternal.mm      |  27 +---
 NativeScript/runtime/PromiseProxy.cpp       |  81 +----------
 NativeScript/runtime/Runtime.mm             |  76 +---------
 NativeScript/runtime/TSHelpers.cpp          | 130 +----------------
 NativeScript/runtime/WeakRef.cpp            |  23 +--
 NativeScript/runtime/js/blob-url.js         |  59 ++++++++
 NativeScript/runtime/js/class-extends.js    |  13 ++
 NativeScript/runtime/js/error-events.js     |  81 +++++++++++
 NativeScript/runtime/js/events.js           | 129 +++++++++++++++++
 NativeScript/runtime/js/inline-functions.js | 101 +++++++++++++
 NativeScript/runtime/js/promise-proxy.js    |  69 +++++++++
 NativeScript/runtime/js/require-factory.js  |  10 ++
 NativeScript/runtime/js/smart-stringify.js  |  19 +++
 NativeScript/runtime/js/ts-helpers.js       | 107 ++++++++++++++
 NativeScript/runtime/js/weak-ref.js         |   9 ++
 package.json                                |   3 +-
 tools/js2c-inputs.xcfilelist                |  11 ++
 tools/js2c-outputs.xcfilelist               |   2 +
 tools/js2c.mjs                              | 148 ++++++++++++++++++++
 v8ios.xcodeproj/project.pbxproj             |  37 +++++
 28 files changed, 945 insertions(+), 721 deletions(-)
 create mode 100644 NativeScript/runtime/BuiltinLoader.cpp
 create mode 100644 NativeScript/runtime/BuiltinLoader.h
 create mode 100644 NativeScript/runtime/js/blob-url.js
 create mode 100644 NativeScript/runtime/js/class-extends.js
 create mode 100644 NativeScript/runtime/js/error-events.js
 create mode 100644 NativeScript/runtime/js/events.js
 create mode 100644 NativeScript/runtime/js/inline-functions.js
 create mode 100644 NativeScript/runtime/js/promise-proxy.js
 create mode 100644 NativeScript/runtime/js/require-factory.js
 create mode 100644 NativeScript/runtime/js/smart-stringify.js
 create mode 100644 NativeScript/runtime/js/ts-helpers.js
 create mode 100644 NativeScript/runtime/js/weak-ref.js
 create mode 100644 tools/js2c-inputs.xcfilelist
 create mode 100644 tools/js2c-outputs.xcfilelist
 create mode 100644 tools/js2c.mjs

diff --git a/.gitignore b/.gitignore
index fbfa1d78..01fd062c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,6 +37,9 @@ Thumbs.db
 # VSCode
 .vscode
 
+# Generated by tools/js2c.mjs (Xcode "Generate RuntimeBuiltins" build phase)
+NativeScript/runtime/generated/
+
 # Other
 node_modules/
 package-lock.json
diff --git a/NativeScript/runtime/BuiltinLoader.cpp b/NativeScript/runtime/BuiltinLoader.cpp
new file mode 100644
index 00000000..e89dc175
--- /dev/null
+++ b/NativeScript/runtime/BuiltinLoader.cpp
@@ -0,0 +1,83 @@
+#include "BuiltinLoader.h"
+
+#include <mutex>
+#include <vector>
+
+#include "Helpers.h"
+
+using namespace v8;
+
+namespace tns {
+
+namespace {
+
+// Process-wide bytecode cache shared across isolates (main + workers).
+std::mutex builtinCacheMutex;
+std::vector<uint8_t> builtinCache[static_cast<unsigned>(BuiltinId::kCount)];
+
+}  // namespace
+
+MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
+                                            BuiltinId id) {
+  Isolate* isolate = v8::Isolate::GetCurrent();
+  const BuiltinSource& builtin = GetBuiltinSource(id);
+  const unsigned index = static_cast<unsigned>(id);
+
+  // Copy the blob out so the shared slot can be refreshed concurrently while
+  // this compile still reads from the copy.
+  std::vector<uint8_t> blob;
+  {
+    std::lock_guard<std::mutex> lock(builtinCacheMutex);
+    blob = builtinCache[index];
+  }
+
+  ScriptOrigin origin(tns::ToV8String(isolate, builtin.name),
+                      0,      // line offset
+                      0,      // column offset
+                      false,  // shared_cross_origin
+                      -1,     // script_id
+                      Local<Value>(),
+                      false,  // is_opaque
+                      false,  // is_wasm
+                      false   // is_module
+  );
+  Local<v8::String> sourceText = tns::ToV8String(
+      isolate, builtin.source, static_cast<int>(builtin.length));
+
+  Local<Script> script;
+  if (!blob.empty()) {
+    // The Source owns and deletes the CachedData object; BufferNotOwned keeps
+    // the underlying bytes (our copy) out of its hands.
+    auto* cachedData = new ScriptCompiler::CachedData(
+        blob.data(), static_cast<int>(blob.size()),
+        ScriptCompiler::CachedData::BufferNotOwned);
+    ScriptCompiler::Source source(sourceText, origin, cachedData);
+    if (ScriptCompiler::Compile(context, &source,
+                                ScriptCompiler::kConsumeCodeCache)
+            .ToLocal(&script) &&
+        !cachedData->rejected) {
+      return script->Run(context);
+    }
+    // Rejected cache (e.g. produced under different flags): fall through and
+    // recompile eagerly so the refreshed blob covers inner functions again.
+  }
+
+  ScriptCompiler::Source source(sourceText, origin);
+  if (!ScriptCompiler::Compile(context, &source, ScriptCompiler::kEagerCompile)
+           .ToLocal(&script)) {
+    return MaybeLocal<Value>();
+  }
+
+  std::unique_ptr<ScriptCompiler::CachedData> produced(
+      ScriptCompiler::CreateCodeCache(script->GetUnboundScript()));
+  if (produced != nullptr && produced->data != nullptr &&
+      produced->length > 0) {
+    std::lock_guard<std::mutex> lock(builtinCacheMutex);
+    builtinCache[index].assign(produced->data,
+                               produced->data + produced->length);
+  }
+
+  return script->Run(context);
+}
+
+}  // namespace tns
diff --git a/NativeScript/runtime/BuiltinLoader.h b/NativeScript/runtime/BuiltinLoader.h
new file mode 100644
index 00000000..e1a804a5
--- /dev/null
+++ b/NativeScript/runtime/BuiltinLoader.h
@@ -0,0 +1,23 @@
+#ifndef BuiltinLoader_h
+#define BuiltinLoader_h
+
+#include "Common.h"
+#include "RuntimeBuiltins.h"
+
+namespace tns {
+
+class BuiltinLoader {
+ public:
+  // Compiles and runs the builtin script identified by id in the given context
+  // and returns its completion value. Scripts carry an "internal/<name>.js"
+  // origin so runtime frames are identifiable in stack traces. Compilation goes
+  // through a process-wide bytecode cache: the first run in the process
+  // compiles eagerly and populates the cache, later isolates (workers) consume
+  // it instead of re-parsing the source.
+  static v8::MaybeLocal<v8::Value> RunBuiltin(v8::Local<v8::Context> context,
+                                              BuiltinId id);
+};
+
+}  // namespace tns
+
+#endif /* BuiltinLoader_h */
diff --git a/NativeScript/runtime/ClassBuilder.mm b/NativeScript/runtime/ClassBuilder.mm
index 4b7a552b..75936775 100644
--- a/NativeScript/runtime/ClassBuilder.mm
+++ b/NativeScript/runtime/ClassBuilder.mm
@@ -3,6 +3,7 @@
 #include <numeric>
 #include <sstream>
 #include "ArgConverter.h"
+#include "BuiltinLoader.h"
 #include "Caches.h"
 #include "FastEnumerationAdapter.h"
 #include "Helpers.h"
@@ -162,27 +163,10 @@
     return;
   }
 
-  std::string extendsFuncScript = "(function() { "
-                                  "    function __extends(d, b) { "
-                                  "         for (var p in b) {"
-                                  "             if (b.hasOwnProperty(p)) {"
-                                  "                 d[p] = b[p];"
-                                  "             }"
-                                  "         }"
-                                  "         function __() { this.constructor = d; }"
-                                  "         d.prototype = b === null ? Object.create(b) : "
-                                  "(__.prototype = b.prototype, new __());"
-                                  "    } "
-                                  "    return __extends;"
-                                  "})()";
-
-  Local<Script> script;
-  tns::Assert(Script::Compile(context, tns::ToV8String(isolate, extendsFuncScript.c_str()))
-                  .ToLocal(&script),
-              isolate);
-
   Local<Value> extendsFunc;
-  tns::Assert(script->Run(context).ToLocal(&extendsFunc) && extendsFunc->IsFunction(), isolate);
+  tns::Assert(BuiltinLoader::RunBuiltin(context, BuiltinId::kClassExtends).ToLocal(&extendsFunc) &&
+                  extendsFunc->IsFunction(),
+              isolate);
 
   cache->OriginalExtendsFunc =
       std::make_unique<Persistent<v8::Function>>(isolate, extendsFunc.As<v8::Function>());
diff --git a/NativeScript/runtime/ErrorEvents.cpp b/NativeScript/runtime/ErrorEvents.cpp
index deccc8ef..c64755a9 100644
--- a/NativeScript/runtime/ErrorEvents.cpp
+++ b/NativeScript/runtime/ErrorEvents.cpp
@@ -1,5 +1,6 @@
 #include "ErrorEvents.h"
 
+#include "BuiltinLoader.h"
 #include "Caches.h"
 #include "Helpers.h"
 #include "NativeScriptException.h"
@@ -31,103 +32,15 @@ void ErrorEvents::Init(Local<Context> context) {
   // terminal tail — and returns three closures bound to that backing store.
   // ErrorEvent/PromiseRejectionEvent subclass the Event captured off globalThis
   // at init time, which runs before any user code.
-  std::string source = R"(
-    (function (globalTarget, nativeReportFatal) {
-      "use strict";
-      var g = globalThis;
-      var Event = g.Event;
-
-      function ErrorEvent(type, opts) {
-        opts = opts || {};
-        Event.call(this, type, opts);
-        this.message = opts.message !== undefined ? String(opts.message) : "";
-        this.filename = opts.filename !== undefined ? String(opts.filename) : "";
-        this.lineno = opts.lineno !== undefined ? (opts.lineno | 0) : 0;
-        this.colno = opts.colno !== undefined ? (opts.colno | 0) : 0;
-        this.error = opts.error !== undefined ? opts.error : null;
-      }
-      ErrorEvent.prototype = Object.create(Event.prototype);
-      ErrorEvent.prototype.constructor = ErrorEvent;
-
-      function PromiseRejectionEvent(type, opts) {
-        opts = opts || {};
-        Event.call(this, type, opts);
-        this.promise = opts.promise;
-        this.reason = opts.reason;
-      }
-      PromiseRejectionEvent.prototype = Object.create(Event.prototype);
-      PromiseRejectionEvent.prototype.constructor = PromiseRejectionEvent;
-
-      // A listener that throws must not stop other listeners: route the thrown
-      // value to the native fatal tail instead of ever recursively dispatching
-      // another `error` event from inside dispatch.
-      globalTarget._installListenerErrorReporter(function (e) {
-        try { nativeReportFatal(e, (e && e.stack) || ""); } catch (ignored) {}
-      });
-
-      g.reportError = function (e) {
-        if (arguments.length === 0) {
-          throw new TypeError("Failed to execute 'reportError': 1 argument required, but only 0 present.");
-        }
-        var ev = new ErrorEvent("error", {
-          message: (e && e.message !== undefined && e.message !== null) ? String(e.message) : String(e),
-          error: e,
-          cancelable: true
-        });
-        if (globalTarget.dispatchEvent(ev)) {
-          nativeReportFatal(e, (e && e.stack) || "");
-        }
-      };
-
-      g.ErrorEvent = ErrorEvent;
-      g.PromiseRejectionEvent = PromiseRejectionEvent;
-
-      // Closures called by C++. They never look up globalThis.dispatchEvent, so
-      // they keep working even if app code overwrites it.
-      function dispatchErrorEvent(error, message, stack) {
-        var ev = new ErrorEvent("error", {
-          message: message !== undefined && message !== null ? String(message) : "",
-          error: error,
-          cancelable: true
-        });
-        globalTarget.dispatchEvent(ev);
-        return ev.defaultPrevented;
-      }
-      function dispatchUnhandledRejection(promise, reason) {
-        var ev = new PromiseRejectionEvent("unhandledrejection", {
-          promise: promise,
-          reason: reason,
-          cancelable: true
-        });
-        globalTarget.dispatchEvent(ev);
-        return ev.defaultPrevented;
-      }
-      function dispatchRejectionHandled(promise, reason) {
-        var ev = new PromiseRejectionEvent("rejectionhandled", {
-          promise: promise,
-          reason: reason,
-          cancelable: false
-        });
-        globalTarget.dispatchEvent(ev);
-      }
-
-      return [dispatchErrorEvent, dispatchUnhandledRejection, dispatchRejectionHandled];
-    })
-  )";
-
   Isolate* isolate = v8::Isolate::GetCurrent();
 
   auto cache = Caches::Get(isolate);
   tns::Assert(cache != nullptr && cache->GlobalEventTarget != nullptr, isolate);
   Local<Object> globalTarget = cache->GlobalEventTarget->Get(isolate);
 
-  Local<Script> script;
-  bool success = Script::Compile(context, tns::ToV8String(isolate, source))
-                     .ToLocal(&script);
-  tns::Assert(success && !script.IsEmpty(), isolate);
-
   Local<Value> result;
-  success = script->Run(context).ToLocal(&result);
+  bool success = BuiltinLoader::RunBuiltin(context, BuiltinId::kErrorEvents)
+                     .ToLocal(&result);
   tns::Assert(success && result->IsFunction(), isolate);
 
   Local<v8::Function> iife = result.As<v8::Function>();
diff --git a/NativeScript/runtime/Events.cpp b/NativeScript/runtime/Events.cpp
index f504c9fe..d75791b7 100644
--- a/NativeScript/runtime/Events.cpp
+++ b/NativeScript/runtime/Events.cpp
@@ -1,5 +1,6 @@
 #include "Events.h"
 
+#include "BuiltinLoader.h"
 #include "Caches.h"
 #include "Helpers.h"
 
@@ -15,147 +16,11 @@ void Events::Init(Local<Context> context) {
   // survives app code overwriting globalThis.dispatchEvent. The error-events
   // layer (ErrorEvents::Init) runs immediately after and installs the native
   // listener-error reporter through _installListenerErrorReporter.
-  std::string source = R"(
-    (function () {
-      "use strict";
-      var g = globalThis;
-
-      function Event(type, opts) {
-        opts = opts || {};
-        this.type = String(type);
-        this.bubbles = !!opts.bubbles;
-        this.cancelable = !!opts.cancelable;
-        this.composed = !!opts.composed;
-        this.defaultPrevented = false;
-        this.target = null;
-        this.currentTarget = null;
-        this._stopPropagation = false;
-        this._stopImmediate = false;
-      }
-      Event.prototype.preventDefault = function () {
-        if (this.cancelable) { this.defaultPrevented = true; }
-      };
-      Event.prototype.stopPropagation = function () { this._stopPropagation = true; };
-      Event.prototype.stopImmediatePropagation = function () {
-        this._stopPropagation = true;
-        this._stopImmediate = true;
-      };
-
-      // A listener that throws must not stop other listeners: route the thrown
-      // value to the native fatal tail instead of ever recursively dispatching
-      // another `error` event from inside dispatch. The error-events layer
-      // installs the real reporter via _installListenerErrorReporter (before any
-      // user code runs); until then a thrown listener is swallowed.
-      var reportListenerError = function (e) {};
-
-      function EventTargetImpl() { this._listeners = Object.create(null); }
-      EventTargetImpl.prototype.addEventListener = function (type, callback, options) {
-        if (callback === null || callback === undefined) { return; }
-        type = String(type);
-        var capture = false, once = false;
-        if (typeof options === "boolean") {
-          capture = options;
-        } else if (options && typeof options === "object") {
-          capture = !!options.capture;
-          once = !!options.once;
-        }
-        var list = this._listeners[type];
-        if (!list) { list = this._listeners[type] = []; }
-        for (var i = 0; i < list.length; i++) {
-          if (list[i].callback === callback && list[i].capture === capture) { return; }
-        }
-        list.push({ callback: callback, once: once, capture: capture });
-      };
-      EventTargetImpl.prototype.removeEventListener = function (type, callback, options) {
-        type = String(type);
-        var capture = false;
-        if (typeof options === "boolean") {
-          capture = options;
-        } else if (options && typeof options === "object") {
-          capture = !!options.capture;
-        }
-        var list = this._listeners[type];
-        if (!list) { return; }
-        for (var i = 0; i < list.length; i++) {
-          if (list[i].callback === callback && list[i].capture === capture) {
-            list.splice(i, 1);
-            return;
-          }
-        }
-      };
-      EventTargetImpl.prototype.dispatchEvent = function (event) {
-        event.target = this;
-        event.currentTarget = this;
-        var list = this._listeners[event.type];
-        if (list) {
-          // Snapshot so listeners added during dispatch are not invoked and
-          // registration order is preserved.
-          var snapshot = list.slice();
-          for (var i = 0; i < snapshot.length; i++) {
-            var entry = snapshot[i];
-            var idx = list.indexOf(entry);
-            if (idx === -1) { continue; }  // removed since snapshot
-            if (entry.once) { list.splice(idx, 1); }
-            var cb = entry.callback;
-            try {
-              if (typeof cb === "function") {
-                cb.call(this, event);
-              } else if (cb && typeof cb.handleEvent === "function") {
-                cb.handleEvent(event);
-              }
-            } catch (e) {
-              reportListenerError(e);
-            }
-            if (event._stopImmediate) { break; }
-          }
-        }
-        event.currentTarget = null;
-        return !event.defaultPrevented;
-      };
-
-      // Internal EventTarget instance backing the global. globalThis's prototype
-      // is intentionally NOT made an EventTarget; only the three methods are
-      // bound onto it.
-      var globalTarget = new EventTargetImpl();
-      // Called by the error-events layer to install the native listener-error
-      // reporter into this closure. One-shot: the backing target leaks to app
-      // code via event.target, so the hook removes itself after the install
-      // (which happens during runtime init, before any user code runs).
-      globalTarget._installListenerErrorReporter = function (fn) {
-        reportListenerError = fn;
-        delete globalTarget._installListenerErrorReporter;
-      };
-      g.addEventListener = function (type, callback, options) {
-        return globalTarget.addEventListener(type, callback, options);
-      };
-      g.removeEventListener = function (type, callback, options) {
-        return globalTarget.removeEventListener(type, callback, options);
-      };
-      g.dispatchEvent = function (event) {
-        return globalTarget.dispatchEvent(event);
-      };
-
-      function EventTarget() { EventTargetImpl.call(this); }
-      EventTarget.prototype.addEventListener = EventTargetImpl.prototype.addEventListener;
-      EventTarget.prototype.removeEventListener = EventTargetImpl.prototype.removeEventListener;
-      EventTarget.prototype.dispatchEvent = EventTargetImpl.prototype.dispatchEvent;
-
-      g.Event = Event;
-      g.EventTarget = EventTarget;
-
-      return globalTarget;
-    })
-  )";
-
   Isolate* isolate = v8::Isolate::GetCurrent();
 
-  Local<Script> script;
-  bool success = Script::Compile(context, tns::ToV8String(isolate, source))
-                     .ToLocal(&script);
-  tns::Assert(success && !script.IsEmpty(), isolate);
-
   Local<Value> result;
-  success = script->Run(context).ToLocal(&result);
+  bool success =
+      BuiltinLoader::RunBuiltin(context, BuiltinId::kEvents).ToLocal(&result);
   tns::Assert(success && result->IsFunction(), isolate);
 
   Local<v8::Function> iife = result.As<v8::Function>();
diff --git a/NativeScript/runtime/Helpers.mm b/NativeScript/runtime/Helpers.mm
index 46436d9d..5328e39a 100644
--- a/NativeScript/runtime/Helpers.mm
+++ b/NativeScript/runtime/Helpers.mm
@@ -10,6 +10,7 @@
 #include <fstream>
 #include <locale>
 #include <sstream>
+#include "BuiltinLoader.h"
 #include "Caches.h"
 #include "NativeScriptException.h"
 #include "Runtime.h"
@@ -491,43 +492,13 @@
     return caches->SmartJSONStringifyFunc->Get(isolate);
   }
 
-  std::string smartStringifyFunctionScript =
-      "(function () {\n"
-      "    function smartStringify(object) {\n"
-      "        const seen = [];\n"
-      "        var replacer = function (key, value) {\n"
-      "            if (value != null && typeof value == \"object\") {\n"
-      "                if (seen.indexOf(value) >= 0) {\n"
-      "                    if (key) {\n"
-      "                        return \"[Circular]\";\n"
-      "                    }\n"
-      "                    return;\n"
-      "                }\n"
-      "                seen.push(value);\n"
-      "            }\n"
-      "            return value;\n"
-      "        };\n"
-      "        return JSON.stringify(object, replacer, 2);\n"
-      "    }\n"
-      "    return smartStringify;\n"
-      "})();";
-
-  Local<v8::String> source = tns::ToV8String(isolate, smartStringifyFunctionScript);
   Local<Context> context = isolate->GetCurrentContext();
 
-  Local<Script> script;
-  bool success = Script::Compile(context, source).ToLocal(&script);
-  tns::Assert(success, isolate);
-
-  if (script.IsEmpty()) {
-    return Local<v8::Function>();
-  }
-
   Local<Value> result;
-  success = script->Run(context).ToLocal(&result);
+  bool success = BuiltinLoader::RunBuiltin(context, BuiltinId::kSmartStringify).ToLocal(&result);
   tns::Assert(success, isolate);
 
-  if (result.IsEmpty() && !result->IsFunction()) {
+  if (result.IsEmpty() || !result->IsFunction()) {
     return Local<v8::Function>();
   }
 
diff --git a/NativeScript/runtime/InlineFunctions.cpp b/NativeScript/runtime/InlineFunctions.cpp
index dc9b63c9..abce884f 100644
--- a/NativeScript/runtime/InlineFunctions.cpp
+++ b/NativeScript/runtime/InlineFunctions.cpp
@@ -1,5 +1,6 @@
 #include "InlineFunctions.h"
 
+#include "BuiltinLoader.h"
 #include "Helpers.h"
 
 using namespace v8;
@@ -7,135 +8,11 @@ using namespace v8;
 namespace tns {
 
 void InlineFunctions::Init(Local<Context> context) {
-  std::string inlineFunctionsSource =
-      "Object.assign(global, {"
-      "    CGPointMake(x, y) {"
-      "        return new CGPoint({ x, y });"
-      "    },"
-      "    CGRectMake(x, y, width, height) {"
-      "        return new CGRect({ origin: { x, y }, size: { width, height } "
-      "});"
-      "    },"
-      "    CGSizeMake(width, height) {"
-      "        return new CGSize({ width, height });"
-      "    },"
-      "    UIEdgeInsetsMake(top, left, bottom, right) {"
-      "        return new UIEdgeInsets({ top, left, bottom, right });"
-      "    },"
-      "    NSMakeRange(location, length) {"
-      "        return new NSRange({ location, length });"
-      "    },"
-      ""
-      "    __decorate(decorators, target, key, desc) {"
-      "        var c = arguments.length, r = c < 3 ? target : desc === null ? "
-      "desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;"
-      "        if (typeof Reflect === \"object\" && typeof Reflect.decorate "
-      "=== \"function\") r = Reflect.decorate(decorators, target, key, desc);"
-      "        else for (var i = decorators.length - 1; i >= 0; i--) if (d = "
-      "decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : "
-      "d(target, key)) || r;"
-      "        return c > 3 && r && Object.defineProperty(target, key, r), r;"
-      "    },"
-      "    __param(paramIndex, decorator) {"
-      "        return function (target, key) { decorator(target, key, "
-      "paramIndex); }"
-      "    },"
-      ""
-      "    ObjCClass() {"
-      "        var protocols = Array.from(arguments);"
-      "        return function (target) {"
-      "            if (protocols.length > 0) {"
-      "                target.ObjCProtocols = (target.ObjCProtocols && "
-      "target.ObjCProtocols instanceof Array ? "
-      "target.ObjCProtocols.concat(protocols) : protocols);"
-      "            }"
-      "        }"
-      "    },"
-      "    ObjCMethod() {"
-      "        var name = arguments[0];"
-      "        var hasName = (name !== undefined && typeof name === "
-      "\"string\");"
-      "        var returnType = (hasName ? arguments[1] : arguments[0]);"
-      ""
-      "        return function (target, propertyKey, descriptor) {"
-      "            if (!target.constructor.ObjCExposedMethods) {"
-      "                target.constructor.ObjCExposedMethods = {};"
-      "            }"
-      "            if (!target.constructor.ObjCExposedMethods[propertyKey]) {"
-      "                target.constructor.ObjCExposedMethods[propertyKey] = {};"
-      "            }"
-      "            target.constructor.ObjCExposedMethods[propertyKey].returns "
-      "= returnType || interop.types.void;"
-      ""
-      "            if (hasName && name !== propertyKey) {"
-      "                target.constructor.ObjCExposedMethods[name] = "
-      "target.constructor.ObjCExposedMethods[propertyKey];"
-      "                delete "
-      "target.constructor.ObjCExposedMethods[propertyKey];"
-      ""
-      "                target[name] = function () { "
-      "                    return this[propertyKey].apply(this, arguments);"
-      "                }"
-      "            }"
-      "        }"
-      "    },"
-      "    ObjC() {"
-      "        var args = Array.from(arguments);"
-      ""
-      "        return function (target, propertyKey, descriptor) {"
-      "            if (propertyKey === undefined) {"
-      "                return ObjCClass.apply(this, args)(target);"
-      "            }"
-      ""
-      "            ObjCMethod.apply(this, args)(target, propertyKey, "
-      "descriptor);"
-      "        };"
-      "    },"
-      "    ObjCParam(type) {"
-      "        return function (target, propertyKey, parameterIndex) {"
-      "            if (!target.constructor.ObjCExposedMethods) {"
-      "                target.constructor.ObjCExposedMethods = {};"
-      "            }"
-      "            if (!target.constructor.ObjCExposedMethods[propertyKey]) {"
-      "                target.constructor.ObjCExposedMethods[propertyKey] = {};"
-      "            }"
-      "            var exposedMethod = "
-      "target.constructor.ObjCExposedMethods[propertyKey];"
-      "            if (!exposedMethod.params) {"
-      "                exposedMethod.params = [];"
-      "            }"
-      "            exposedMethod.params[parameterIndex] = type || "
-      "interop.types.void;"
-      "        };"
-      "    },"
-      ""
-      "});"
-      ""
-      "Object.defineProperty(global, \"__tsEnum\", {"
-      "    writable: false,"
-      "    enumerable: false,"
-      "    configurable: false,"
-      "    value: function(obj) {"
-      "        var result = {};"
-      "        for (var key of Object.keys(obj)) {"
-      "            result[key] = obj[key];"
-      "            result[obj[key]] = key;"
-      "        }"
-      "        return result;"
-      "    }"
-      "});";
-
   Isolate* isolate = v8::Isolate::GetCurrent();
 
-  Local<Script> script;
-  if (!Script::Compile(context, tns::ToV8String(isolate, inlineFunctionsSource))
-           .ToLocal(&script)) {
-    tns::Assert(false, isolate);
-  }
-  tns::Assert(!script.IsEmpty(), isolate);
-
   Local<Value> result;
-  if (!script->Run(context).ToLocal(&result)) {
+  if (!BuiltinLoader::RunBuiltin(context, BuiltinId::kInlineFunctions)
+           .ToLocal(&result)) {
     tns::Assert(false, isolate);
   }
 }
diff --git a/NativeScript/runtime/ModuleInternal.mm b/NativeScript/runtime/ModuleInternal.mm
index a26b2be1..afabf8b2 100644
--- a/NativeScript/runtime/ModuleInternal.mm
+++ b/NativeScript/runtime/ModuleInternal.mm
@@ -5,6 +5,7 @@
 #include <unistd.h>
 #include <utime.h>
 #include <string>
+#include "BuiltinLoader.h"
 #include "Caches.h"
 #include "DevFlags.h"
 #include "Helpers.h"
@@ -80,32 +81,14 @@ bool IsESModule(const std::string& path) {
 }
 
 ModuleInternal::ModuleInternal(Local<Context> context) {
-  std::string requireFactoryScript = "(function() { "
-                                     "    function require_factory(requireInternal, dirName) { "
-                                     "        return function require(modulePath) { "
-                                     "            if(global.__pauseOnNextRequire) {  debugger; "
-                                     "global.__pauseOnNextRequire = false; }"
-                                     "            return requireInternal(modulePath, dirName); "
-                                     "        } "
-                                     "    } "
-                                     "    return require_factory; "
-                                     "})()";
-
   Isolate* isolate = v8::Isolate::GetCurrent();
   Local<Object> global = context->Global();
-  Local<Script> script;
   TryCatch tc(isolate);
-  if (!Script::Compile(context, tns::ToV8String(isolate, requireFactoryScript.c_str()))
-           .ToLocal(&script) &&
-      tc.HasCaught()) {
-    tns::LogError(isolate, tc);
-    Log(@"FATAL: Failed to compile require factory script");
-    return;
-  }
-
   Local<Value> result;
-  if (!script->Run(context).ToLocal(&result) && tc.HasCaught()) {
-    tns::LogError(isolate, tc);
+  if (!BuiltinLoader::RunBuiltin(context, BuiltinId::kRequireFactory).ToLocal(&result)) {
+    if (tc.HasCaught()) {
+      tns::LogError(isolate, tc);
+    }
     Log(@"FATAL: Failed to run require factory script");
     return;
   }
diff --git a/NativeScript/runtime/PromiseProxy.cpp b/NativeScript/runtime/PromiseProxy.cpp
index 65ac19eb..6ac8c56a 100644
--- a/NativeScript/runtime/PromiseProxy.cpp
+++ b/NativeScript/runtime/PromiseProxy.cpp
@@ -2,6 +2,7 @@
 
 #include <CoreFoundation/CoreFoundation.h>
 
+#include "BuiltinLoader.h"
 #include "Helpers.h"
 #include "Runtime.h"
 
@@ -21,87 +22,11 @@ static void IsRuntimeRunloopCallback(const FunctionCallbackInfo<Value>& args) {
 }
 
 void PromiseProxy::Init(v8::Local<v8::Context> context) {
-  std::string source = R"(
-        // Run a Promise's callbacks on the thread that created it, but only when
-        // that thread is the runtime loop. A Promise created on a background
-        // thread settles on whichever thread resolves it, because the background
-        // run loop may be dormant and marshaling a resolution to it would hang.
-        (function(isRuntimeRunloop) {
-            global.Promise = new Proxy(global.Promise, {
-                construct: function(target, args) {
-                    let origFunc = args[0];
-                    let runloop = CFRunLoopGetCurrent();
-                    let originIsRuntimeLoop = isRuntimeRunloop();
-
-                    let promise = new target(function(resolve, reject) {
-                        function isFulfilled() {
-                            return !resolve;
-                        }
-                        function markFulfilled() {
-                            origFunc = null;
-                            resolve = null;
-                            reject = null;
-                        }
-                        origFunc(value => {
-                            if (isFulfilled()) {
-                                return;
-                            }
-                            const resolveCall = resolve.bind(this, value);
-                            if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
-                                markFulfilled();
-                                resolveCall();
-                            } else {
-                                CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, resolveCall);
-                                CFRunLoopWakeUp(runloop);
-                                markFulfilled();
-                            }
-                        }, reason => {
-                            if (isFulfilled()) {
-                                return;
-                            }
-                            const rejectCall = reject.bind(this, reason);
-                            if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
-                                markFulfilled();
-                                rejectCall();
-                            } else {
-                                CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, rejectCall);
-                                CFRunLoopWakeUp(runloop);
-                                markFulfilled();
-                            }
-                        });
-                    });
-
-                    return new Proxy(promise, {
-                        get: function(target, name) {
-                            let orig = target[name];
-                            if (name === "then" || name === "catch" || name === "finally") {
-                                return orig.bind(target);
-                            }
-                            return typeof orig === 'function' ? function(x) {
-                                if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
-                                    orig.bind(target, x)();
-                                    return target;
-                                }
-                                CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, orig.bind(target, x));
-                                CFRunLoopWakeUp(runloop);
-                                return target;
-                            } : orig;
-                        }
-                    });
-                }
-            });
-        })
-    )";
-
   Isolate* isolate = v8::Isolate::GetCurrent();
 
-  Local<Script> script;
-  bool success = Script::Compile(context, tns::ToV8String(isolate, source))
-                     .ToLocal(&script);
-  tns::Assert(success && !script.IsEmpty(), isolate);
-
   Local<Value> result;
-  success = script->Run(context).ToLocal(&result);
+  bool success = BuiltinLoader::RunBuiltin(context, BuiltinId::kPromiseProxy)
+                     .ToLocal(&result);
   tns::Assert(success && result->IsFunction(), isolate);
 
   Local<v8::Function> installProxy = result.As<v8::Function>();
diff --git a/NativeScript/runtime/Runtime.mm b/NativeScript/runtime/Runtime.mm
index 9e16fbd0..c7fdead9 100644
--- a/NativeScript/runtime/Runtime.mm
+++ b/NativeScript/runtime/Runtime.mm
@@ -2,6 +2,7 @@
 #include <chrono>
 #include <string>
 #include "ArgConverter.h"
+#include "BuiltinLoader.h"
 #include "Caches.h"
 #include "Console.h"
 #include "Constants.h"
@@ -364,75 +365,12 @@ void DisposeIsolateWhenPossible(Isolate* isolate) {
   Console::Init(context);
   WeakRef::Init(context);
 
-  auto blob_methods = R"js(
-    const BLOB_STORE = new Map();
-    URL.createObjectURL = function (object, options = null) {
-        try {
-            if (object instanceof Blob || object instanceof File) {
-                const id = NSUUID.UUID().UUIDString.toLowerCase();
-                const ret = `blob:nativescript/${id}`;
-                BLOB_STORE.set(ret, {
-                    blob: object,
-                    type: object?.type,
-                    ext: options?.ext,
-                });
-                return ret;
-            }
-        } catch (error) {
-            return null;
-        }
-        return null;
-    };
-    URL.revokeObjectURL = function (url) {
-        BLOB_STORE.delete(url);
-    };
-    const InternalAccessor = class {};
-    InternalAccessor.getData = function (url) {
-        return BLOB_STORE.get(url);
-    };
-    URL.InternalAccessor = InternalAccessor;
-    Object.defineProperty(URL.prototype, 'searchParams', {
-        get() {
-            if (this._searchParams == null) {
-                this._searchParams = new URLSearchParams(this.search);
-                Object.defineProperty(this._searchParams, '_url', {
-                    enumerable: false,
-                    writable: false,
-                    value: this,
-                });
-                this._searchParams._append = this._searchParams.append;
-                this._searchParams.append = function (name, value) {
-                    this._append(name, value);
-                    this._url.search = this.toString();
-                };
-                this._searchParams._delete = this._searchParams.delete;
-                this._searchParams.delete = function (name) {
-                    this._delete(name);
-                    this._url.search = this.toString();
-                };
-                this._searchParams._set = this._searchParams.set;
-                this._searchParams.set = function (name, value) {
-                    this._set(name, value);
-                    this._url.search = this.toString();
-                };
-                this._searchParams._sort = this._searchParams.sort;
-                this._searchParams.sort = function () {
-                    this._sort();
-                    this._url.search = this.toString();
-                };
-            }
-            return this._searchParams;
-        },
-    });
-    )js";
-
-  v8::Local<v8::Script> script;
-  auto done = v8::Script::Compile(context, ToV8String(isolate, blob_methods)).ToLocal(&script);
-
-  v8::Local<v8::Value> outVal;
-  if (done) {
-    done = script->Run(context).ToLocal(&outVal);
-  }
+  // URL blob support (internal/blob-url.js); failures are tolerated, matching
+  // the previous compile-and-run-if-possible behavior.
+  v8::Local<v8::Value> blobMethodsResult;
+  bool blobMethodsOk =
+      BuiltinLoader::RunBuiltin(context, BuiltinId::kBlobUrl).ToLocal(&blobMethodsResult);
+  (void)blobMethodsOk;
 
   this->moduleInternal_ = std::make_unique<ModuleInternal>(context);
 
diff --git a/NativeScript/runtime/TSHelpers.cpp b/NativeScript/runtime/TSHelpers.cpp
index 413e5c1a..73b892f3 100644
--- a/NativeScript/runtime/TSHelpers.cpp
+++ b/NativeScript/runtime/TSHelpers.cpp
@@ -2,6 +2,7 @@
 
 #include <string>
 
+#include "BuiltinLoader.h"
 #include "Helpers.h"
 
 using namespace v8;
@@ -23,135 +24,12 @@ void TSHelpers::Init(Local<Context> context) {
   // }(BaseClass));
   // var obj = new InheritingClass();
 
-  std::string source =
-      "(() => {"
-      "    var __originalExtends = global.__extends;"
-      "    var __extends = (Child, Parent) => {"
-      "        var extendingNativeClass = !!Parent.extend && "
-      "(Parent.extend.toString().indexOf(\"[native code]\") > -1);"
-      "        if (!extendingNativeClass) {"
-      "            __extends_ts(Child, Parent);"
-      "            return;"
-      "        }"
-      ""
-      "        if (Parent.__isPrototypeImplementationObject) {"
-      "            throw new Error(\"Can not extend an already extended native "
-      "object.\");"
-      "        }"
-      ""
-      "        function extend(thiz) {"
-      "            var child = thiz.__proto__.__child;"
-      "            if (!child.__extended) {"
-      "                var parent = thiz.__proto__.__parent;"
-      "                child.__extended = parent.extend(child.prototype, {"
-      "                    name: child.name,"
-      "                    protocols: child.ObjCProtocols || [],"
-      "                    exposedMethods: child.ObjCExposedMethods || {}"
-      "                });"
-      "                child[Symbol.hasInstance] = function (instance) {"
-      "                    return instance instanceof this.__extended;"
-      "                }"
-      "            }"
-      "            return child.__extended;"
-      "        }"
-      ""
-      "        Parent.call = function (thiz) {"
-      "            var Extended = extend(thiz);"
-      "            thiz.__container__ = true;"
-      "            if (arguments.length > 1) {"
-      "                thiz.__proto__ = new "
-      "(Function.prototype.bind.apply(Extended, "
-      "[null].concat(Array.prototype.slice.call(arguments, 1))));"
-      "            } else {"
-      "                thiz.__proto__ = new Extended()"
-      "            }"
-      "            return thiz.__proto__;"
-      "        };"
-      ""
-      "        Parent.apply = function (thiz, args) {"
-      "            var Extended = extend(thiz);"
-      "            thiz.__container__ = true;"
-      "            if (args && args.length > 0) {"
-      "                thiz.__proto__ = new "
-      "(Function.prototype.bind.apply(Extended, [null].concat(args)));"
-      "            } else {"
-      "                thiz.__proto__ = new Extended();"
-      "            }"
-      "            return thiz.__proto__;"
-      "        };"
-      ""
-      "        __extends_ns(Child, Parent);"
-      "        Child.__isPrototypeImplementationObject = true;"
-      "        Child.__proto__ = Parent;"
-      "        Child.prototype.__parent = Parent;"
-      "        Child.prototype.__child = Child;"
-      ""
-      "        if (__originalExtends) {"
-      "            __originalExtends(Child, Parent);"
-      "        }"
-      "    };"
-      ""
-      "    var __extends_ts = function (child, parent) {"
-      "        extendStaticFunctions(child, parent);"
-      "        assignPrototypeFromParentToChild(parent, child);"
-      "    };"
-      ""
-      "    var __extends_ns = function (child, parent) {"
-      "        if (!parent.extend) {"
-      "            assignPropertiesFromParentToChild(parent, child);"
-      "        }"
-      ""
-      "        assignPrototypeFromParentToChild(parent, child);"
-      "    };"
-      ""
-      "    var extendStaticFunctions ="
-      "        Object.setPrototypeOf"
-      "        || (hasInternalProtoProperty() && function (child, parent) { "
-      "child.__proto__ = parent; })"
-      "        || assignPropertiesFromParentToChild;"
-      ""
-      "    function hasInternalProtoProperty() {"
-      "        return { __proto__: [] } instanceof Array;"
-      "    }"
-      ""
-      "    function assignPropertiesFromParentToChild(parent, child) {"
-      "        for (var property in parent) {"
-      "            if (parent.hasOwnProperty(property)) {"
-      "                child[property] = parent[property];"
-      "            }"
-      "        }"
-      "    }"
-      ""
-      "    function assignPrototypeFromParentToChild(parent, child) {"
-      "        function __() {"
-      "            this.constructor = child;"
-      "        }"
-      ""
-      "        if (parent === null) {"
-      "            child.prototype = Object.create(null);"
-      "        } else {"
-      "            __.prototype = parent.prototype;"
-      "            child.prototype = new __();"
-      "        }"
-      "    }"
-      ""
-      "    Object.defineProperty(global, \"__extends\", { value: __extends, "
-      "writable: false });"
-      "})()";
-
   Isolate* isolate = v8::Isolate::GetCurrent();
-  Local<Script> script;
   TryCatch tc(isolate);
-  if (!Script::Compile(context, tns::ToV8String(isolate, source.c_str()))
-           .ToLocal(&script) &&
-      tc.HasCaught()) {
-    tns::LogError(isolate, tc);
-    tns::Assert(false, isolate);
-  }
-  tns::Assert(!script.IsEmpty(), isolate);
-
   Local<Value> result;
-  if (!script->Run(context).ToLocal(&result) && tc.HasCaught()) {
+  if (!BuiltinLoader::RunBuiltin(context, BuiltinId::kTsHelpers)
+           .ToLocal(&result) &&
+      tc.HasCaught()) {
     tns::LogError(isolate, tc);
     tns::Assert(false, isolate);
   }
diff --git a/NativeScript/runtime/WeakRef.cpp b/NativeScript/runtime/WeakRef.cpp
index 4f29d5c2..9796f4a3 100644
--- a/NativeScript/runtime/WeakRef.cpp
+++ b/NativeScript/runtime/WeakRef.cpp
@@ -1,5 +1,6 @@
 #include "WeakRef.h"
 
+#include "BuiltinLoader.h"
 #include "Helpers.h"
 
 using namespace v8;
@@ -9,26 +10,10 @@ namespace tns {
 void WeakRef::Init(Local<Context> context) {
   Isolate* isolate = v8::Isolate::GetCurrent();
 
-  std::string source = R"(
-        global.WeakRef.prototype.get = global.WeakRef.prototype.deref;
-        global.WeakRef.prototype.__hasWarnedAboutClear = false;
-        global.WeakRef.prototype.clear = () => {
-            if(global.WeakRef.prototype.__hasWarnedAboutClear) {
-                return;
-            }
-            global.WeakRef.prototype.__hasWarnedAboutClear = true;
-            console.warn('WeakRef.clear() is non-standard and has been deprecated. It does nothing and the call can be safely removed.');
-        }
-    )";
-
-  Local<Script> script;
-  bool success = Script::Compile(context, tns::ToV8String(isolate, source))
-                     .ToLocal(&script);
-  tns::Assert(success && !script.IsEmpty(), isolate);
-
   Local<Value> result;
-  success = script->Run(context).ToLocal(&result);
+  bool success =
+      BuiltinLoader::RunBuiltin(context, BuiltinId::kWeakRef).ToLocal(&result);
   tns::Assert(success, isolate);
 }
 
-}  // namespace tns
\ No newline at end of file
+}  // namespace tns
diff --git a/NativeScript/runtime/js/blob-url.js b/NativeScript/runtime/js/blob-url.js
new file mode 100644
index 00000000..6f414f85
--- /dev/null
+++ b/NativeScript/runtime/js/blob-url.js
@@ -0,0 +1,59 @@
+const BLOB_STORE = new Map();
+URL.createObjectURL = function (object, options = null) {
+    try {
+        if (object instanceof Blob || object instanceof File) {
+            const id = NSUUID.UUID().UUIDString.toLowerCase();
+            const ret = `blob:nativescript/${id}`;
+            BLOB_STORE.set(ret, {
+                blob: object,
+                type: object?.type,
+                ext: options?.ext,
+            });
+            return ret;
+        }
+    } catch (error) {
+        return null;
+    }
+    return null;
+};
+URL.revokeObjectURL = function (url) {
+    BLOB_STORE.delete(url);
+};
+const InternalAccessor = class {};
+InternalAccessor.getData = function (url) {
+    return BLOB_STORE.get(url);
+};
+URL.InternalAccessor = InternalAccessor;
+Object.defineProperty(URL.prototype, 'searchParams', {
+    get() {
+        if (this._searchParams == null) {
+            this._searchParams = new URLSearchParams(this.search);
+            Object.defineProperty(this._searchParams, '_url', {
+                enumerable: false,
+                writable: false,
+                value: this,
+            });
+            this._searchParams._append = this._searchParams.append;
+            this._searchParams.append = function (name, value) {
+                this._append(name, value);
+                this._url.search = this.toString();
+            };
+            this._searchParams._delete = this._searchParams.delete;
+            this._searchParams.delete = function (name) {
+                this._delete(name);
+                this._url.search = this.toString();
+            };
+            this._searchParams._set = this._searchParams.set;
+            this._searchParams.set = function (name, value) {
+                this._set(name, value);
+                this._url.search = this.toString();
+            };
+            this._searchParams._sort = this._searchParams.sort;
+            this._searchParams.sort = function () {
+                this._sort();
+                this._url.search = this.toString();
+            };
+        }
+        return this._searchParams;
+    },
+});
diff --git a/NativeScript/runtime/js/class-extends.js b/NativeScript/runtime/js/class-extends.js
new file mode 100644
index 00000000..40984f24
--- /dev/null
+++ b/NativeScript/runtime/js/class-extends.js
@@ -0,0 +1,13 @@
+(function() { 
+    function __extends(d, b) { 
+         for (var p in b) {
+             if (b.hasOwnProperty(p)) {
+                 d[p] = b[p];
+             }
+         }
+         function __() { this.constructor = d; }
+         d.prototype = b === null ? Object.create(b) : 
+(__.prototype = b.prototype, new __());
+    } 
+    return __extends;
+})()
diff --git a/NativeScript/runtime/js/error-events.js b/NativeScript/runtime/js/error-events.js
new file mode 100644
index 00000000..13fe428b
--- /dev/null
+++ b/NativeScript/runtime/js/error-events.js
@@ -0,0 +1,81 @@
+(function (globalTarget, nativeReportFatal) {
+  "use strict";
+  var g = globalThis;
+  var Event = g.Event;
+
+  function ErrorEvent(type, opts) {
+    opts = opts || {};
+    Event.call(this, type, opts);
+    this.message = opts.message !== undefined ? String(opts.message) : "";
+    this.filename = opts.filename !== undefined ? String(opts.filename) : "";
+    this.lineno = opts.lineno !== undefined ? (opts.lineno | 0) : 0;
+    this.colno = opts.colno !== undefined ? (opts.colno | 0) : 0;
+    this.error = opts.error !== undefined ? opts.error : null;
+  }
+  ErrorEvent.prototype = Object.create(Event.prototype);
+  ErrorEvent.prototype.constructor = ErrorEvent;
+
+  function PromiseRejectionEvent(type, opts) {
+    opts = opts || {};
+    Event.call(this, type, opts);
+    this.promise = opts.promise;
+    this.reason = opts.reason;
+  }
+  PromiseRejectionEvent.prototype = Object.create(Event.prototype);
+  PromiseRejectionEvent.prototype.constructor = PromiseRejectionEvent;
+
+  // A listener that throws must not stop other listeners: route the thrown
+  // value to the native fatal tail instead of ever recursively dispatching
+  // another `error` event from inside dispatch.
+  globalTarget._installListenerErrorReporter(function (e) {
+    try { nativeReportFatal(e, (e && e.stack) || ""); } catch (ignored) {}
+  });
+
+  g.reportError = function (e) {
+    if (arguments.length === 0) {
+      throw new TypeError("Failed to execute 'reportError': 1 argument required, but only 0 present.");
+    }
+    var ev = new ErrorEvent("error", {
+      message: (e && e.message !== undefined && e.message !== null) ? String(e.message) : String(e),
+      error: e,
+      cancelable: true
+    });
+    if (globalTarget.dispatchEvent(ev)) {
+      nativeReportFatal(e, (e && e.stack) || "");
+    }
+  };
+
+  g.ErrorEvent = ErrorEvent;
+  g.PromiseRejectionEvent = PromiseRejectionEvent;
+
+  // Closures called by C++. They never look up globalThis.dispatchEvent, so
+  // they keep working even if app code overwrites it.
+  function dispatchErrorEvent(error, message, stack) {
+    var ev = new ErrorEvent("error", {
+      message: message !== undefined && message !== null ? String(message) : "",
+      error: error,
+      cancelable: true
+    });
+    globalTarget.dispatchEvent(ev);
+    return ev.defaultPrevented;
+  }
+  function dispatchUnhandledRejection(promise, reason) {
+    var ev = new PromiseRejectionEvent("unhandledrejection", {
+      promise: promise,
+      reason: reason,
+      cancelable: true
+    });
+    globalTarget.dispatchEvent(ev);
+    return ev.defaultPrevented;
+  }
+  function dispatchRejectionHandled(promise, reason) {
+    var ev = new PromiseRejectionEvent("rejectionhandled", {
+      promise: promise,
+      reason: reason,
+      cancelable: false
+    });
+    globalTarget.dispatchEvent(ev);
+  }
+
+  return [dispatchErrorEvent, dispatchUnhandledRejection, dispatchRejectionHandled];
+})
diff --git a/NativeScript/runtime/js/events.js b/NativeScript/runtime/js/events.js
new file mode 100644
index 00000000..8cb1a78b
--- /dev/null
+++ b/NativeScript/runtime/js/events.js
@@ -0,0 +1,129 @@
+(function () {
+  "use strict";
+  var g = globalThis;
+
+  function Event(type, opts) {
+    opts = opts || {};
+    this.type = String(type);
+    this.bubbles = !!opts.bubbles;
+    this.cancelable = !!opts.cancelable;
+    this.composed = !!opts.composed;
+    this.defaultPrevented = false;
+    this.target = null;
+    this.currentTarget = null;
+    this._stopPropagation = false;
+    this._stopImmediate = false;
+  }
+  Event.prototype.preventDefault = function () {
+    if (this.cancelable) { this.defaultPrevented = true; }
+  };
+  Event.prototype.stopPropagation = function () { this._stopPropagation = true; };
+  Event.prototype.stopImmediatePropagation = function () {
+    this._stopPropagation = true;
+    this._stopImmediate = true;
+  };
+
+  // A listener that throws must not stop other listeners: route the thrown
+  // value to the native fatal tail instead of ever recursively dispatching
+  // another `error` event from inside dispatch. The error-events layer
+  // installs the real reporter via _installListenerErrorReporter (before any
+  // user code runs); until then a thrown listener is swallowed.
+  var reportListenerError = function (e) {};
+
+  function EventTargetImpl() { this._listeners = Object.create(null); }
+  EventTargetImpl.prototype.addEventListener = function (type, callback, options) {
+    if (callback === null || callback === undefined) { return; }
+    type = String(type);
+    var capture = false, once = false;
+    if (typeof options === "boolean") {
+      capture = options;
+    } else if (options && typeof options === "object") {
+      capture = !!options.capture;
+      once = !!options.once;
+    }
+    var list = this._listeners[type];
+    if (!list) { list = this._listeners[type] = []; }
+    for (var i = 0; i < list.length; i++) {
+      if (list[i].callback === callback && list[i].capture === capture) { return; }
+    }
+    list.push({ callback: callback, once: once, capture: capture });
+  };
+  EventTargetImpl.prototype.removeEventListener = function (type, callback, options) {
+    type = String(type);
+    var capture = false;
+    if (typeof options === "boolean") {
+      capture = options;
+    } else if (options && typeof options === "object") {
+      capture = !!options.capture;
+    }
+    var list = this._listeners[type];
+    if (!list) { return; }
+    for (var i = 0; i < list.length; i++) {
+      if (list[i].callback === callback && list[i].capture === capture) {
+        list.splice(i, 1);
+        return;
+      }
+    }
+  };
+  EventTargetImpl.prototype.dispatchEvent = function (event) {
+    event.target = this;
+    event.currentTarget = this;
+    var list = this._listeners[event.type];
+    if (list) {
+      // Snapshot so listeners added during dispatch are not invoked and
+      // registration order is preserved.
+      var snapshot = list.slice();
+      for (var i = 0; i < snapshot.length; i++) {
+        var entry = snapshot[i];
+        var idx = list.indexOf(entry);
+        if (idx === -1) { continue; }  // removed since snapshot
+        if (entry.once) { list.splice(idx, 1); }
+        var cb = entry.callback;
+        try {
+          if (typeof cb === "function") {
+            cb.call(this, event);
+          } else if (cb && typeof cb.handleEvent === "function") {
+            cb.handleEvent(event);
+          }
+        } catch (e) {
+          reportListenerError(e);
+        }
+        if (event._stopImmediate) { break; }
+      }
+    }
+    event.currentTarget = null;
+    return !event.defaultPrevented;
+  };
+
+  // Internal EventTarget instance backing the global. globalThis's prototype
+  // is intentionally NOT made an EventTarget; only the three methods are
+  // bound onto it.
+  var globalTarget = new EventTargetImpl();
+  // Called by the error-events layer to install the native listener-error
+  // reporter into this closure. One-shot: the backing target leaks to app
+  // code via event.target, so the hook removes itself after the install
+  // (which happens during runtime init, before any user code runs).
+  globalTarget._installListenerErrorReporter = function (fn) {
+    reportListenerError = fn;
+    delete globalTarget._installListenerErrorReporter;
+  };
+  g.addEventListener = function (type, callback, options) {
+    return globalTarget.addEventListener(type, callback, options);
+  };
+  g.removeEventListener = function (type, callback, options) {
+    return globalTarget.removeEventListener(type, callback, options);
+  };
+  g.dispatchEvent = function (event) {
+    return globalTarget.dispatchEvent(event);
+  };
+
+  function EventTarget() { EventTargetImpl.call(this); }
+  EventTarget.prototype.addEventListener = EventTargetImpl.prototype.addEventListener;
+  EventTarget.prototype.removeEventListener = EventTargetImpl.prototype.removeEventListener;
+  EventTarget.prototype.dispatchEvent = EventTargetImpl.prototype.dispatchEvent;
+
+  g.Event = Event;
+  g.EventTarget = EventTarget;
+
+  return globalTarget;
+})
diff --git a/NativeScript/runtime/js/inline-functions.js b/NativeScript/runtime/js/inline-functions.js
new file mode 100644
index 00000000..72a99b62
--- /dev/null
+++ b/NativeScript/runtime/js/inline-functions.js
@@ -0,0 +1,101 @@
+Object.assign(global, {
+    CGPointMake(x, y) {
+        return new CGPoint({ x, y });
+    },
+    CGRectMake(x, y, width, height) {
+        return new CGRect({ origin: { x, y }, size: { width, height } });
+    },
+    CGSizeMake(width, height) {
+        return new CGSize({ width, height });
+    },
+    UIEdgeInsetsMake(top, left, bottom, right) {
+        return new UIEdgeInsets({ top, left, bottom, right });
+    },
+    NSMakeRange(location, length) {
+        return new NSRange({ location, length });
+    },
+
+    __decorate(decorators, target, key, desc) {
+        var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
+        if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
+        else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
+        return c > 3 && r && Object.defineProperty(target, key, r), r;
+    },
+    __param(paramIndex, decorator) {
+        return function (target, key) { decorator(target, key, paramIndex); }
+    },
+
+    ObjCClass() {
+        var protocols = Array.from(arguments);
+        return function (target) {
+            if (protocols.length > 0) {
+                target.ObjCProtocols = (target.ObjCProtocols && target.ObjCProtocols instanceof Array ? target.ObjCProtocols.concat(protocols) : protocols);
+            }
+        }
+    },
+    ObjCMethod() {
+        var name = arguments[0];
+        var hasName = (name !== undefined && typeof name === "string");
+        var returnType = (hasName ? arguments[1] : arguments[0]);
+
+        return function (target, propertyKey, descriptor) {
+            if (!target.constructor.ObjCExposedMethods) {
+                target.constructor.ObjCExposedMethods = {};
+            }
+            if (!target.constructor.ObjCExposedMethods[propertyKey]) {
+                target.constructor.ObjCExposedMethods[propertyKey] = {};
+            }
+            target.constructor.ObjCExposedMethods[propertyKey].returns = returnType || interop.types.void;
+
+            if (hasName && name !== propertyKey) {
+                target.constructor.ObjCExposedMethods[name] = target.constructor.ObjCExposedMethods[propertyKey];
+                delete target.constructor.ObjCExposedMethods[propertyKey];
+
+                target[name] = function () { 
+                    return this[propertyKey].apply(this, arguments);
+                }
+            }
+        }
+    },
+    ObjC() {
+        var args = Array.from(arguments);
+
+        return function (target, propertyKey, descriptor) {
+            if (propertyKey === undefined) {
+                return ObjCClass.apply(this, args)(target);
+            }
+
+            ObjCMethod.apply(this, args)(target, propertyKey, descriptor);
+        };
+    },
+    ObjCParam(type) {
+        return function (target, propertyKey, parameterIndex) {
+            if (!target.constructor.ObjCExposedMethods) {
+                target.constructor.ObjCExposedMethods = {};
+            }
+            if (!target.constructor.ObjCExposedMethods[propertyKey]) {
+                target.constructor.ObjCExposedMethods[propertyKey] = {};
+            }
+            var exposedMethod = target.constructor.ObjCExposedMethods[propertyKey];
+            if (!exposedMethod.params) {
+                exposedMethod.params = [];
+            }
+            exposedMethod.params[parameterIndex] = type || interop.types.void;
+        };
+    },
+
+});
+
+Object.defineProperty(global, "__tsEnum", {
+    writable: false,
+    enumerable: false,
+    configurable: false,
+    value: function(obj) {
+        var result = {};
+        for (var key of Object.keys(obj)) {
+            result[key] = obj[key];
+            result[obj[key]] = key;
+        }
+        return result;
+    }
+});
diff --git a/NativeScript/runtime/js/promise-proxy.js b/NativeScript/runtime/js/promise-proxy.js
new file mode 100644
index 00000000..b88f0b73
--- /dev/null
+++ b/NativeScript/runtime/js/promise-proxy.js
@@ -0,0 +1,69 @@
+// Run a Promise's callbacks on the thread that created it, but only when
+// that thread is the runtime loop. A Promise created on a background
+// thread settles on whichever thread resolves it, because the background
+// run loop may be dormant and marshaling a resolution to it would hang.
+(function(isRuntimeRunloop) {
+    global.Promise = new Proxy(global.Promise, {
+        construct: function(target, args) {
+            let origFunc = args[0];
+            let runloop = CFRunLoopGetCurrent();
+            let originIsRuntimeLoop = isRuntimeRunloop();
+
+            let promise = new target(function(resolve, reject) {
+                function isFulfilled() {
+                    return !resolve;
+                }
+                function markFulfilled() {
+                    origFunc = null;
+                    resolve = null;
+                    reject = null;
+                }
+                origFunc(value => {
+                    if (isFulfilled()) {
+                        return;
+                    }
+                    const resolveCall = resolve.bind(this, value);
+                    if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
+                        markFulfilled();
+                        resolveCall();
+                    } else {
+                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, resolveCall);
+                        CFRunLoopWakeUp(runloop);
+                        markFulfilled();
+                    }
+                }, reason => {
+                    if (isFulfilled()) {
+                        return;
+                    }
+                    const rejectCall = reject.bind(this, reason);
+                    if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
+                        markFulfilled();
+                        rejectCall();
+                    } else {
+                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, rejectCall);
+                        CFRunLoopWakeUp(runloop);
+                        markFulfilled();
+                    }
+                });
+            });
+
+            return new Proxy(promise, {
+                get: function(target, name) {
+                    let orig = target[name];
+                    if (name === "then" || name === "catch" || name === "finally") {
+                        return orig.bind(target);
+                    }
+                    return typeof orig === 'function' ? function(x) {
+                        if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
+                            orig.bind(target, x)();
+                            return target;
+                        }
+                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, orig.bind(target, x));
+                        CFRunLoopWakeUp(runloop);
+                        return target;
+                    } : orig;
+                }
+            });
+        }
+    });
+})
diff --git a/NativeScript/runtime/js/require-factory.js b/NativeScript/runtime/js/require-factory.js
new file mode 100644
index 00000000..af08aa5c
--- /dev/null
+++ b/NativeScript/runtime/js/require-factory.js
@@ -0,0 +1,10 @@
+(function() { 
+    function require_factory(requireInternal, dirName) { 
+        return function require(modulePath) { 
+            if(global.__pauseOnNextRequire) {  debugger; 
+global.__pauseOnNextRequire = false; }
+            return requireInternal(modulePath, dirName); 
+        } 
+    } 
+    return require_factory; 
+})()
diff --git a/NativeScript/runtime/js/smart-stringify.js b/NativeScript/runtime/js/smart-stringify.js
new file mode 100644
index 00000000..0ff7f09d
--- /dev/null
+++ b/NativeScript/runtime/js/smart-stringify.js
@@ -0,0 +1,19 @@
+(function () {
+    function smartStringify(object) {
+        const seen = [];
+        var replacer = function (key, value) {
+            if (value != null && typeof value == "object") {
+                if (seen.indexOf(value) >= 0) {
+                    if (key) {
+                        return "[Circular]";
+                    }
+                    return;
+                }
+                seen.push(value);
+            }
+            return value;
+        };
+        return JSON.stringify(object, replacer, 2);
+    }
+    return smartStringify;
+})();
diff --git a/NativeScript/runtime/js/ts-helpers.js b/NativeScript/runtime/js/ts-helpers.js
new file mode 100644
index 00000000..38d43820
--- /dev/null
+++ b/NativeScript/runtime/js/ts-helpers.js
@@ -0,0 +1,107 @@
+(() => {
+    var __originalExtends = global.__extends;
+    var __extends = (Child, Parent) => {
+        var extendingNativeClass = !!Parent.extend && (Parent.extend.toString().indexOf("[native code]") > -1);
+        if (!extendingNativeClass) {
+            __extends_ts(Child, Parent);
+            return;
+        }
+
+        if (Parent.__isPrototypeImplementationObject) {
+            throw new Error("Can not extend an already extended native object.");
+        }
+
+        function extend(thiz) {
+            var child = thiz.__proto__.__child;
+            if (!child.__extended) {
+                var parent = thiz.__proto__.__parent;
+                child.__extended = parent.extend(child.prototype, {
+                    name: child.name,
+                    protocols: child.ObjCProtocols || [],
+                    exposedMethods: child.ObjCExposedMethods || {}
+                });
+                child[Symbol.hasInstance] = function (instance) {
+                    return instance instanceof this.__extended;
+                }
+            }
+            return child.__extended;
+        }
+
+        Parent.call = function (thiz) {
+            var Extended = extend(thiz);
+            thiz.__container__ = true;
+            if (arguments.length > 1) {
+                thiz.__proto__ = new (Function.prototype.bind.apply(Extended, [null].concat(Array.prototype.slice.call(arguments, 1))));
+            } else {
+                thiz.__proto__ = new Extended()
+            }
+            return thiz.__proto__;
+        };
+
+        Parent.apply = function (thiz, args) {
+            var Extended = extend(thiz);
+            thiz.__container__ = true;
+            if (args && args.length > 0) {
+                thiz.__proto__ = new (Function.prototype.bind.apply(Extended, [null].concat(args)));
+            } else {
+                thiz.__proto__ = new Extended();
+            }
+            return thiz.__proto__;
+        };
+
+        __extends_ns(Child, Parent);
+        Child.__isPrototypeImplementationObject = true;
+        Child.__proto__ = Parent;
+        Child.prototype.__parent = Parent;
+        Child.prototype.__child = Child;
+
+        if (__originalExtends) {
+            __originalExtends(Child, Parent);
+        }
+    };
+
+    var __extends_ts = function (child, parent) {
+        extendStaticFunctions(child, parent);
+        assignPrototypeFromParentToChild(parent, child);
+    };
+
+    var __extends_ns = function (child, parent) {
+        if (!parent.extend) {
+            assignPropertiesFromParentToChild(parent, child);
+        }
+
+        assignPrototypeFromParentToChild(parent, child);
+    };
+
+    var extendStaticFunctions =
+        Object.setPrototypeOf
+        || (hasInternalProtoProperty() && function (child, parent) { child.__proto__ = parent; })
+        || assignPropertiesFromParentToChild;
+
+    function hasInternalProtoProperty() {
+        return { __proto__: [] } instanceof Array;
+    }
+
+    function assignPropertiesFromParentToChild(parent, child) {
+        for (var property in parent) {
+            if (parent.hasOwnProperty(property)) {
+                child[property] = parent[property];
+            }
+        }
+    }
+
+    function assignPrototypeFromParentToChild(parent, child) {
+        function __() {
+            this.constructor = child;
+        }
+
+        if (parent === null) {
+            child.prototype = Object.create(null);
+        } else {
+            __.prototype = parent.prototype;
+            child.prototype = new __();
+        }
+    }
+
+    Object.defineProperty(global, "__extends", { value: __extends, writable: false });
+})()
diff --git a/NativeScript/runtime/js/weak-ref.js b/NativeScript/runtime/js/weak-ref.js
new file mode 100644
index 00000000..01e9fe03
--- /dev/null
+++ b/NativeScript/runtime/js/weak-ref.js
@@ -0,0 +1,9 @@
+global.WeakRef.prototype.get = global.WeakRef.prototype.deref;
+global.WeakRef.prototype.__hasWarnedAboutClear = false;
+global.WeakRef.prototype.clear = () => {
+    if(global.WeakRef.prototype.__hasWarnedAboutClear) {
+        return;
+    }
+    global.WeakRef.prototype.__hasWarnedAboutClear = true;
+    console.warn('WeakRef.clear() is non-standard and has been deprecated. It does nothing and the call can be safely removed.');
+}
diff --git a/package.json b/package.json
index c7971dce..48485134 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
   "devDependencies": {
     "conventional-changelog-cli": "^2.1.1",
     "dayjs": "^1.11.7",
+    "esbuild": "0.28.1",
     "husky": "^9.0.11",
     "lint-staged": "^15.2.7",
     "semver": "^7.5.0"
@@ -42,4 +43,4 @@
       "clang-format -i"
     ]
   }
-}
\ No newline at end of file
+}
diff --git a/tools/js2c-inputs.xcfilelist b/tools/js2c-inputs.xcfilelist
new file mode 100644
index 00000000..3d31d102
--- /dev/null
+++ b/tools/js2c-inputs.xcfilelist
@@ -0,0 +1,11 @@
+$(SRCROOT)/tools/js2c.mjs
+$(SRCROOT)/NativeScript/runtime/js/blob-url.js
+$(SRCROOT)/NativeScript/runtime/js/class-extends.js
+$(SRCROOT)/NativeScript/runtime/js/error-events.js
+$(SRCROOT)/NativeScript/runtime/js/events.js
+$(SRCROOT)/NativeScript/runtime/js/inline-functions.js
+$(SRCROOT)/NativeScript/runtime/js/promise-proxy.js
+$(SRCROOT)/NativeScript/runtime/js/require-factory.js
+$(SRCROOT)/NativeScript/runtime/js/smart-stringify.js
+$(SRCROOT)/NativeScript/runtime/js/ts-helpers.js
+$(SRCROOT)/NativeScript/runtime/js/weak-ref.js
diff --git a/tools/js2c-outputs.xcfilelist b/tools/js2c-outputs.xcfilelist
new file mode 100644
index 00000000..80d435af
--- /dev/null
+++ b/tools/js2c-outputs.xcfilelist
@@ -0,0 +1,2 @@
+$(SRCROOT)/NativeScript/runtime/generated/RuntimeBuiltins.h
+$(SRCROOT)/NativeScript/runtime/generated/RuntimeBuiltins.cpp
diff --git a/tools/js2c.mjs b/tools/js2c.mjs
new file mode 100644
index 00000000..7c9cd3e6
--- /dev/null
+++ b/tools/js2c.mjs
@@ -0,0 +1,148 @@
+#!/usr/bin/env node
+// Converts the runtime's builtin .js sources into a generated C++ table
+// (RuntimeBuiltins.h / RuntimeBuiltins.cpp) compiled into NativeScript.framework.
+// Invoked by the "Generate RuntimeBuiltins" build phase of the NativeScript target.
+import { readFileSync, writeFileSync, mkdirSync, existsSync } from 'node:fs';
+import { basename, join } from 'node:path';
+import { parseArgs } from 'node:util';
+
+const USAGE = `usage: node tools/js2c.mjs --out-dir <dir> [--minify] <file.js>...
+
+Generates <dir>/RuntimeBuiltins.h and <dir>/RuntimeBuiltins.cpp from the given
+builtin JavaScript sources. Builtin ids and script-origin names derive from the
+file names (promise-proxy.js -> BuiltinId::kPromiseProxy, "internal/promise-proxy.js").
+
+options:
+  --out-dir <dir>  output directory for the generated files (required)
+  --minify         minify sources with esbuild (whitespace + syntax only)
+  --help           show this message`;
+
+let args;
+try {
+  args = parseArgs({
+    options: {
+      'out-dir': { type: 'string' },
+      minify: { type: 'boolean', default: false },
+      help: { type: 'boolean', default: false },
+    },
+    allowPositionals: true,
+  });
+} catch (e) {
+  console.error(e.message);
+  console.error(USAGE);
+  process.exit(1);
+}
+if (args.values.help) {
+  console.log(USAGE);
+  process.exit(0);
+}
+const outDir = args.values['out-dir'];
+const inputs = args.positionals;
+if (!outDir || inputs.length === 0) {
+  console.error('error: --out-dir and at least one input file are required');
+  console.error(USAGE);
+  process.exit(1);
+}
+
+// Stable ordering regardless of shell glob order, so output never churns.
+inputs.sort((a, b) => basename(a).localeCompare(basename(b)));
+
+const builtins = [];
+for (const file of inputs) {
+  if (!existsSync(file)) {
+    console.error(`error: no such file: ${file}`);
+    process.exit(1);
+  }
+  const stem = basename(file).replace(/\.js$/, '');
+  if (!/^[a-z0-9]+(-[a-z0-9]+)*$/.test(stem)) {
+    console.error(`error: file name must be kebab-case .js: ${file}`);
+    process.exit(1);
+  }
+  let source = readFileSync(file, 'utf8');
+  if (args.values.minify) {
+    // Lazy import: esbuild is only needed when minification is requested.
+    const esbuild = await import('esbuild');
+    source = (await esbuild.transform(source, {
+      minifyWhitespace: true,
+      minifySyntax: true,
+      legalComments: 'none',
+    })).code;
+  }
+  const id = 'k' + stem.replace(/(^|-)([a-z0-9])/g, (_, __, c) => c.toUpperCase());
+  builtins.push({ stem, id, origin: `internal/${stem}.js`, source });
+}
+
+const ids = builtins.map((b) => `  ${b.id},`).join('\n');
+const header = `// generated by tools/js2c.mjs — do not edit
+#ifndef RUNTIMEBUILTINS_H_
+#define RUNTIMEBUILTINS_H_
+
+#include <cstddef>
+
+namespace tns {
+
+enum class BuiltinId : unsigned {
+${ids}
+  kCount,
+};
+
+struct BuiltinSource {
+  const char* name;    // script origin, e.g. "internal/promise-proxy.js"
+  const char* source;  // NUL-terminated UTF-8
+  size_t length;       // bytes, excluding the NUL
+};
+
+const BuiltinSource& GetBuiltinSource(BuiltinId id);
+
+}  // namespace tns
+
+#endif  // RUNTIMEBUILTINS_H_
+`;
+
+// Byte arrays sidestep every C string-literal escaping pitfall.
+function toByteArray(name, text) {
+  const bytes = Buffer.from(text, 'utf8');
+  const lines = [];
+  for (let i = 0; i < bytes.length; i += 16) {
+    lines.push('    ' + [...bytes.subarray(i, i + 16)].map((b) => `0x${b.toString(16).padStart(2, '0')},`).join(' '));
+  }
+  return `static const char ${name}[] = {\n${lines.join('\n')}\n    0x00};\n`;
+}
+
+const arrays = builtins
+  .map((b) => `// ${b.stem}.js\n${toByteArray(`kSource${b.id.slice(1)}`, b.source)}`)
+  .join('\n');
+const entries = builtins
+  .map((b) => `    {"${b.origin}", kSource${b.id.slice(1)}, sizeof(kSource${b.id.slice(1)}) - 1},`)
+  .join('\n');
+const impl = `// generated by tools/js2c.mjs — do not edit
+#include "RuntimeBuiltins.h"
+
+namespace tns {
+
+namespace {
+
+${arrays}
+const BuiltinSource kBuiltins[] = {
+${entries}
+};
+
+}  // namespace
+
+const BuiltinSource& GetBuiltinSource(BuiltinId id) {
+  return kBuiltins[static_cast<unsigned>(id)];
+}
+
+}  // namespace tns
+`;
+
+mkdirSync(outDir, { recursive: true });
+// Skip identical writes so downstream compilation isn't invalidated needlessly.
+for (const [name, content] of [['RuntimeBuiltins.h', header], ['RuntimeBuiltins.cpp', impl]]) {
+  const path = join(outDir, name);
+  if (existsSync(path) && readFileSync(path, 'utf8') === content) {
+    continue;
+  }
+  writeFileSync(path, content);
+}
+console.log(`js2c: generated ${builtins.length} builtins into ${outDir}`);
diff --git a/v8ios.xcodeproj/project.pbxproj b/v8ios.xcodeproj/project.pbxproj
index c7b87232..31f7e20a 100644
--- a/v8ios.xcodeproj/project.pbxproj
+++ b/v8ios.xcodeproj/project.pbxproj
@@ -291,6 +291,8 @@
 		C2DDEB90229EAC8300345BFE /* MetadataBuilder.h in Headers */ = {isa = PBXBuildFile; fileRef = C2DDEB67229EAC8100345BFE /* MetadataBuilder.h */; };
 		C2DDEB91229EAC8300345BFE /* FFICall.cpp in Sources */ = {isa = PBXBuildFile; fileRef = C2DDEB68229EAC8100345BFE /* FFICall.cpp */; };
 		C2DDEB92229EAC8300345BFE /* WeakRef.cpp in Sources */ = {isa = PBXBuildFile; fileRef = C2DDEB69229EAC8100345BFE /* WeakRef.cpp */; };
+		4A5C201A2E2B000100000006 /* BuiltinLoader.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4A5C201A2E2B000100000001 /* BuiltinLoader.cpp */; };
+		4A5C201A2E2B000100000007 /* RuntimeBuiltins.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 4A5C201A2E2B000100000003 /* RuntimeBuiltins.cpp */; };
 		C2DDEB93229EAC8300345BFE /* ArgConverter.mm in Sources */ = {isa = PBXBuildFile; fileRef = C2DDEB6A229EAC8200345BFE /* ArgConverter.mm */; };
 		C2DDEB94229EAC8300345BFE /* Console.cpp in Sources */ = {isa = PBXBuildFile; fileRef = C2DDEB6B229EAC8200345BFE /* Console.cpp */; };
 		C2DDEB95229EAC8300345BFE /* SetTimeout.cpp in Sources */ = {isa = PBXBuildFile; fileRef = C2DDEB6C229EAC8200345BFE /* SetTimeout.cpp */; };
@@ -805,6 +807,11 @@
 		C2DDEB67229EAC8100345BFE /* MetadataBuilder.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MetadataBuilder.h; sourceTree = "<group>"; };
 		C2DDEB68229EAC8100345BFE /* FFICall.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = FFICall.cpp; sourceTree = "<group>"; };
 		C2DDEB69229EAC8100345BFE /* WeakRef.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = WeakRef.cpp; sourceTree = "<group>"; };
+		4A5C201A2E2B000100000001 /* BuiltinLoader.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = BuiltinLoader.cpp; sourceTree = "<group>"; };
+		4A5C201A2E2B000100000002 /* BuiltinLoader.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = BuiltinLoader.h; sourceTree = "<group>"; };
+		4A5C201A2E2B000100000003 /* RuntimeBuiltins.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = RuntimeBuiltins.cpp; path = generated/RuntimeBuiltins.cpp; sourceTree = "<group>"; };
+		4A5C201A2E2B000100000004 /* RuntimeBuiltins.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = RuntimeBuiltins.h; path = generated/RuntimeBuiltins.h; sourceTree = "<group>"; };
+		4A5C201A2E2B000100000005 /* js */ = {isa = PBXFileReference; lastKnownFileType = folder; path = js; sourceTree = "<group>"; };
 		C2DDEB6A229EAC8200345BFE /* ArgConverter.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = ArgConverter.mm; sourceTree = "<group>"; };
 		C2DDEB6B229EAC8200345BFE /* Console.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Console.cpp; sourceTree = "<group>"; };
 		C2DDEB6C229EAC8200345BFE /* SetTimeout.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = SetTimeout.cpp; sourceTree = "<group>"; };
@@ -1517,6 +1524,11 @@
 				C298C025233C9AEA000DDF54 /* TSHelpers.cpp */,
 				C2DDEB82229EAC8200345BFE /* WeakRef.h */,
 				C2DDEB69229EAC8100345BFE /* WeakRef.cpp */,
+				4A5C201A2E2B000100000002 /* BuiltinLoader.h */,
+				4A5C201A2E2B000100000001 /* BuiltinLoader.cpp */,
+				4A5C201A2E2B000100000004 /* RuntimeBuiltins.h */,
+				4A5C201A2E2B000100000003 /* RuntimeBuiltins.cpp */,
+				4A5C201A2E2B000100000005 /* js */,
 				3CD1D9BF29AA2C14004C1C21 /* DisposerPHV.mm */,
 				3CD1D9C029AA2C14004C1C21 /* DisposerPHV.h */,
 				C22C092122CA3F370080D176 /* Worker.h */,
@@ -1803,6 +1815,7 @@
 			buildConfigurationList = C2DDEB37229EAB3B00345BFE /* Build configuration list for PBXNativeTarget "NativeScript" */;
 			buildPhases = (
 				C2DDEB2D229EAB3B00345BFE /* Headers */,
+				4A5C201A2E2B000100000008 /* Generate RuntimeBuiltins */,
 				C2DDEB2E229EAB3B00345BFE /* Sources */,
 				C2DDEB2F229EAB3B00345BFE /* Frameworks */,
 				C2DDEB30229EAB3B00345BFE /* Resources */,
@@ -1939,6 +1952,26 @@
 /* End PBXResourcesBuildPhase section */
 
 /* Begin PBXShellScriptBuildPhase section */
+		4A5C201A2E2B000100000008 /* Generate RuntimeBuiltins */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+				"$(SRCROOT)/tools/js2c-inputs.xcfilelist",
+			);
+			inputPaths = (
+			);
+			name = "Generate RuntimeBuiltins";
+			outputFileListPaths = (
+				"$(SRCROOT)/tools/js2c-outputs.xcfilelist",
+			);
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "set -e\nexport PATH=\"$PATH:/opt/homebrew/bin:/usr/local/bin\"\nif ! command -v node >/dev/null 2>&1; then\n  echo \"error: node is required to generate the runtime builtins (tools/js2c.mjs); install Node.js or add it to PATH\" >&2\n  exit 1\nfi\ncd \"${SRCROOT}\"\nnode tools/js2c.mjs --out-dir NativeScript/runtime/generated NativeScript/runtime/js/*.js\n";
+		};
 		2BFE21F02AC1B28000307752 /* Add default metadata */ = {
 			isa = PBXShellScriptBuildPhase;
 			buildActionMask = 2147483647;
@@ -2248,6 +2281,8 @@
 				C20AB5E626E1015300E2B41D /* OneByteStringResource.cpp in Sources */,
 				6573B9CE291FE29F00B0ED7C /* JSIV8ValueConverter.cpp in Sources */,
 				C2DDEB92229EAC8300345BFE /* WeakRef.cpp in Sources */,
+				4A5C201A2E2B000100000006 /* BuiltinLoader.cpp in Sources */,
+				4A5C201A2E2B000100000007 /* RuntimeBuiltins.cpp in Sources */,
 				C2A5F86A2359AEB600074AFA /* ExtVector.cpp in Sources */,
 				AA8C47B22E27114300649BF5 /* ModuleInternalCallbacks.mm in Sources */,
 				C2DDEBAF229EAC8300345BFE /* ObjectManager.mm in Sources */,
@@ -2944,6 +2979,7 @@
 					"$(SRCROOT)/NativeScript/inspector",
 					"$(SRCROOT)/NativeScript/v8runtime",
 					"$(SRCROOT)/NativeScript/jsi",
+					"$(SRCROOT)/NativeScript/runtime/generated",
 				);
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";
@@ -3037,6 +3073,7 @@
 					"$(SRCROOT)/NativeScript/inspector",
 					"$(SRCROOT)/NativeScript/v8runtime",
 					"$(SRCROOT)/NativeScript/jsi",
+					"$(SRCROOT)/NativeScript/runtime/generated",
 				);
 				VERSIONING_SYSTEM = "apple-generic";
 				VERSION_INFO_PREFIX = "";

From 885abe98ecfd12b9dc5fa42f81a4c1972a61dd41 Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@gmail.com>
Date: Thu, 30 Jul 2026 09:38:27 -0300
Subject: [PATCH 2/5] perf: stop re-evaluating enum JS snippets on every access

Interop::WriteValue recompiled and re-ran an enum wrapper's __tsEnum
snippet on every FFI marshal; the value is now memoized on the
EnumDataWrapper. GlobalPropertyGetter did the same on every read of a
JsCode global; the evaluated result is now defined as a real own
property on the global (the interceptor is kNonMasking, so later reads
bypass it entirely), with a reentrancy guard because CreateDataProperty
re-enters the interceptor before the property exists.
---
 NativeScript/runtime/DataWrapper.h      | 14 +++++++++++-
 NativeScript/runtime/Interop.mm         | 30 +++++++++++++------------
 NativeScript/runtime/MetadataBuilder.h  |  5 +++++
 NativeScript/runtime/MetadataBuilder.mm | 15 +++++++++++++
 4 files changed, 49 insertions(+), 15 deletions(-)

diff --git a/NativeScript/runtime/DataWrapper.h b/NativeScript/runtime/DataWrapper.h
index 266a77e9..25cfd37b 100644
--- a/NativeScript/runtime/DataWrapper.h
+++ b/NativeScript/runtime/DataWrapper.h
@@ -157,14 +157,26 @@ class BaseDataWrapper {
 
 class EnumDataWrapper : public BaseDataWrapper {
  public:
-  EnumDataWrapper(std::string jsCode) : jsCode_(jsCode) {}
+  EnumDataWrapper(std::string jsCode)
+      : jsCode_(jsCode), hasCachedValue_(false), cachedValue_(0) {}
 
   const WrapperType Type() { return WrapperType::Enum; }
 
   std::string JSCode() { return jsCode_; }
 
+  // Numeric value memoized by Interop::WriteValue so the enum's JS snippet is
+  // compiled and evaluated at most once per wrapper.
+  bool HasCachedValue() const { return hasCachedValue_; }
+  double CachedValue() const { return cachedValue_; }
+  void SetCachedValue(double value) {
+    cachedValue_ = value;
+    hasCachedValue_ = true;
+  }
+
  private:
   std::string jsCode_;
+  bool hasCachedValue_;
+  double cachedValue_;
 };
 
 class PointerTypeWrapper : public BaseDataWrapper {
diff --git a/NativeScript/runtime/Interop.mm b/NativeScript/runtime/Interop.mm
index 9ad54282..088f8f6c 100644
--- a/NativeScript/runtime/Interop.mm
+++ b/NativeScript/runtime/Interop.mm
@@ -618,23 +618,25 @@ inline bool isBool() {
     if (wrapper != nullptr) {
       if (wrapper->Type() == WrapperType::Enum) {
         EnumDataWrapper* enumWrapper = static_cast<EnumDataWrapper*>(wrapper);
-        Local<Context> context = isolate->GetCurrentContext();
-        std::string jsCode = enumWrapper->JSCode();
-        Local<Script> script;
-        if (!Script::Compile(context, tns::ToV8String(isolate, jsCode)).ToLocal(&script)) {
-          tns::Assert(false, isolate);
-        }
-        tns::Assert(!script.IsEmpty(), isolate);
+        if (!enumWrapper->HasCachedValue()) {
+          Local<Context> context = isolate->GetCurrentContext();
+          std::string jsCode = enumWrapper->JSCode();
+          Local<Script> script;
+          if (!Script::Compile(context, tns::ToV8String(isolate, jsCode)).ToLocal(&script)) {
+            tns::Assert(false, isolate);
+          }
+          tns::Assert(!script.IsEmpty(), isolate);
 
-        Local<Value> result;
-        if (!script->Run(context).ToLocal(&result) && !result.IsEmpty()) {
-          tns::Assert(false, isolate);
-        }
+          Local<Value> result;
+          if (!script->Run(context).ToLocal(&result) && !result.IsEmpty()) {
+            tns::Assert(false, isolate);
+          }
 
-        tns::Assert(result->IsNumber(), isolate);
+          tns::Assert(result->IsNumber(), isolate);
 
-        double value = result.As<Number>()->Value();
-        SetValue(dest, value);
+          enumWrapper->SetCachedValue(result.As<Number>()->Value());
+        }
+        SetValue(dest, enumWrapper->CachedValue());
       } else if (wrapper->Type() == WrapperType::Pointer) {
         PointerWrapper* pointerWrapper = static_cast<PointerWrapper*>(wrapper);
         void* data = pointerWrapper->Data();
diff --git a/NativeScript/runtime/MetadataBuilder.h b/NativeScript/runtime/MetadataBuilder.h
index d648e20a..36f275a6 100644
--- a/NativeScript/runtime/MetadataBuilder.h
+++ b/NativeScript/runtime/MetadataBuilder.h
@@ -127,6 +127,11 @@ class MetadataBuilder {
     GlobalHandlerContext(bool isWorkerThread)
         : isWorkerThread_(isWorkerThread) {}
     bool isWorkerThread_;
+    // Name currently being defined as a real own property on the global from
+    // inside GlobalPropertyGetter. CreateDataProperty performs a lookup that
+    // re-enters the (kNonMasking) interceptor before the property exists, so
+    // the getter must decline for this name to avoid infinite recursion.
+    std::string definingProperty_;
   };
 
   template <class T>
diff --git a/NativeScript/runtime/MetadataBuilder.mm b/NativeScript/runtime/MetadataBuilder.mm
index 4277c596..6efadcec 100644
--- a/NativeScript/runtime/MetadataBuilder.mm
+++ b/NativeScript/runtime/MetadataBuilder.mm
@@ -39,6 +39,13 @@ NamedPropertyHandlerConfiguration config(MetadataBuilder::GlobalPropertyGetter,
   GlobalHandlerContext* ctx = static_cast<GlobalHandlerContext*>(
       info.Data().As<External>()->Value(v8::kExternalPointerTypeTagDefault));
 
+  // Decline while this exact name is being defined as an own property below —
+  // CreateDataProperty's lookup re-enters this interceptor before the property
+  // exists on the global.
+  if (ctx->definingProperty_ == propName && !propName.empty()) {
+    return v8::Intercepted::kNo;
+  }
+
   if (ctx->isWorkerThread_ &&
       std::find(Worker::GlobalFunctions.begin(), Worker::GlobalFunctions.end(), propName) !=
           Worker::GlobalFunctions.end()) {
@@ -138,6 +145,14 @@ NamedPropertyHandlerConfiguration config(MetadataBuilder::GlobalPropertyGetter,
     if (!script->Run(context).ToLocal(&result)) {
       tns::Assert(false, isolate);
     }
+    // Memoize the evaluated value as a real own property: the interceptor is
+    // registered kNonMasking, so later reads of this global bypass it (and the
+    // per-access recompilation of the meta's JS snippet) entirely.
+    ctx->definingProperty_ = propName;
+    bool memoized =
+        context->Global()->CreateDataProperty(context, property, result).FromMaybe(false);
+    (void)memoized;
+    ctx->definingProperty_.clear();
     info.GetReturnValue().Set(result);
   } else if (meta->type() == MetaType::Struct) {
     const StructMeta* structMeta = static_cast<const StructMeta*>(meta);

From 434c1c7a859eba90e45ed2ef3ee4dee980a4a9d9 Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@gmail.com>
Date: Thu, 30 Jul 2026 10:05:12 -0300
Subject: [PATCH 3/5] refactor: compile builtins as function bodies with a
 fixed binding parameter

Adopts Node's internals idiom: every builtin is compiled via
ScriptCompiler::CompileFunction with the single parameter `binding`, and
natives arrive as properties of one bag object that each file
destructures at the top (const { isRuntimeRunloop } = binding). The
visible IIFE wrappers are gone, top-level return is the way a builtin
hands a value back to C++, and the bytecode cache moves to
CreateCodeCacheForFunction.

The parameter name is fixed and hardcoded in BuiltinLoader, so there is
no per-builtin name to mistype in C++; on the JS side an ESLint gate
(no-undef with `binding` and the reachable native globals declared)
catches typos in the destructures, wired into lint-staged. Conventions
are documented in NativeScript/runtime/js/README.md.
---
 NativeScript/runtime/BuiltinLoader.cpp     |  47 +++--
 NativeScript/runtime/BuiltinLoader.h       |  19 +-
 NativeScript/runtime/ErrorEvents.cpp       |  55 ++---
 NativeScript/runtime/Events.cpp            |  20 +-
 NativeScript/runtime/PromiseProxy.cpp      |  26 +--
 NativeScript/runtime/js/README.md          |  37 ++++
 NativeScript/runtime/js/class-extends.js   |   2 -
 NativeScript/runtime/js/error-events.js    | 146 ++++++-------
 NativeScript/runtime/js/events.js          | 234 ++++++++++-----------
 NativeScript/runtime/js/promise-proxy.js   | 118 +++++------
 NativeScript/runtime/js/require-factory.js |   2 -
 NativeScript/runtime/js/smart-stringify.js |  32 ++-
 NativeScript/runtime/js/ts-helpers.js      | 170 ++++++++-------
 eslint.config.mjs                          |  47 +++++
 package.json                               |   5 +
 15 files changed, 529 insertions(+), 431 deletions(-)
 create mode 100644 NativeScript/runtime/js/README.md
 create mode 100644 eslint.config.mjs

diff --git a/NativeScript/runtime/BuiltinLoader.cpp b/NativeScript/runtime/BuiltinLoader.cpp
index e89dc175..c3c5f4d5 100644
--- a/NativeScript/runtime/BuiltinLoader.cpp
+++ b/NativeScript/runtime/BuiltinLoader.cpp
@@ -15,10 +15,12 @@ namespace {
 std::mutex builtinCacheMutex;
 std::vector<uint8_t> builtinCache[static_cast<unsigned>(BuiltinId::kCount)];
 
-}  // namespace
+// Every builtin is compiled as a function body receiving this single, fixed
+// parameter (Node's internalBinding idiom): natives arrive as properties of
+// one bag object and each file destructures what it needs.
+constexpr const char* kBindingParamName = "binding";
 
-MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
-                                            BuiltinId id) {
+MaybeLocal<v8::Function> CompileBuiltin(Local<Context> context, BuiltinId id) {
   Isolate* isolate = v8::Isolate::GetCurrent();
   const BuiltinSource& builtin = GetBuiltinSource(id);
   const unsigned index = static_cast<unsigned>(id);
@@ -43,8 +45,9 @@ MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
   );
   Local<v8::String> sourceText = tns::ToV8String(
       isolate, builtin.source, static_cast<int>(builtin.length));
+  Local<v8::String> params[] = {tns::ToV8String(isolate, kBindingParamName)};
 
-  Local<Script> script;
+  Local<v8::Function> fn;
   if (!blob.empty()) {
     // The Source owns and deletes the CachedData object; BufferNotOwned keeps
     // the underlying bytes (our copy) out of its hands.
@@ -52,24 +55,25 @@ MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
         blob.data(), static_cast<int>(blob.size()),
         ScriptCompiler::CachedData::BufferNotOwned);
     ScriptCompiler::Source source(sourceText, origin, cachedData);
-    if (ScriptCompiler::Compile(context, &source,
-                                ScriptCompiler::kConsumeCodeCache)
-            .ToLocal(&script) &&
+    if (ScriptCompiler::CompileFunction(context, &source, 1, params, 0, nullptr,
+                                        ScriptCompiler::kConsumeCodeCache)
+            .ToLocal(&fn) &&
         !cachedData->rejected) {
-      return script->Run(context);
+      return fn;
     }
     // Rejected cache (e.g. produced under different flags): fall through and
     // recompile eagerly so the refreshed blob covers inner functions again.
   }
 
   ScriptCompiler::Source source(sourceText, origin);
-  if (!ScriptCompiler::Compile(context, &source, ScriptCompiler::kEagerCompile)
-           .ToLocal(&script)) {
-    return MaybeLocal<Value>();
+  if (!ScriptCompiler::CompileFunction(context, &source, 1, params, 0, nullptr,
+                                       ScriptCompiler::kEagerCompile)
+           .ToLocal(&fn)) {
+    return MaybeLocal<v8::Function>();
   }
 
   std::unique_ptr<ScriptCompiler::CachedData> produced(
-      ScriptCompiler::CreateCodeCache(script->GetUnboundScript()));
+      ScriptCompiler::CreateCodeCacheForFunction(fn));
   if (produced != nullptr && produced->data != nullptr &&
       produced->length > 0) {
     std::lock_guard<std::mutex> lock(builtinCacheMutex);
@@ -77,7 +81,24 @@ MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
                                produced->data + produced->length);
   }
 
-  return script->Run(context);
+  return fn;
+}
+
+}  // namespace
+
+MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
+                                            BuiltinId id,
+                                            Local<Value> binding) {
+  Isolate* isolate = v8::Isolate::GetCurrent();
+
+  Local<v8::Function> fn;
+  if (!CompileBuiltin(context, id).ToLocal(&fn)) {
+    return MaybeLocal<Value>();
+  }
+
+  Local<Value> args[] = {binding.IsEmpty() ? v8::Undefined(isolate).As<Value>()
+                                           : binding};
+  return fn->Call(context, v8::Undefined(isolate), 1, args);
 }
 
 }  // namespace tns
diff --git a/NativeScript/runtime/BuiltinLoader.h b/NativeScript/runtime/BuiltinLoader.h
index e1a804a5..7205a81e 100644
--- a/NativeScript/runtime/BuiltinLoader.h
+++ b/NativeScript/runtime/BuiltinLoader.h
@@ -8,14 +8,17 @@ namespace tns {
 
 class BuiltinLoader {
  public:
-  // Compiles and runs the builtin script identified by id in the given context
-  // and returns its completion value. Scripts carry an "internal/<name>.js"
-  // origin so runtime frames are identifiable in stack traces. Compilation goes
-  // through a process-wide bytecode cache: the first run in the process
-  // compiles eagerly and populates the cache, later isolates (workers) consume
-  // it instead of re-parsing the source.
-  static v8::MaybeLocal<v8::Value> RunBuiltin(v8::Local<v8::Context> context,
-                                              BuiltinId id);
+  // Compiles the builtin identified by id as a function body with the single
+  // fixed parameter `binding` (Node's internalBinding idiom), calls it with
+  // the given bag of natives (or undefined when omitted), and returns its
+  // return value. Scripts carry an "internal/<name>.js" origin so runtime
+  // frames are identifiable in stack traces. Compilation goes through a
+  // process-wide bytecode cache: the first run in the process compiles
+  // eagerly and populates the cache, later isolates (workers) consume it
+  // instead of re-parsing the source.
+  static v8::MaybeLocal<v8::Value> RunBuiltin(
+      v8::Local<v8::Context> context, BuiltinId id,
+      v8::Local<v8::Value> binding = v8::Local<v8::Value>());
 };
 
 }  // namespace tns
diff --git a/NativeScript/runtime/ErrorEvents.cpp b/NativeScript/runtime/ErrorEvents.cpp
index c64755a9..2ae6a44b 100644
--- a/NativeScript/runtime/ErrorEvents.cpp
+++ b/NativeScript/runtime/ErrorEvents.cpp
@@ -9,8 +9,9 @@ using namespace v8;
 
 namespace tns {
 
-// Native function handed to the bootstrap IIFE as `nativeReportFatal(error,
-// stackString)`. It runs the terminal tail (shim + fatal log) WITHOUT
+// Native function handed to the error-events builtin as
+// `binding.nativeReportFatal(error, stackString)`. It runs the terminal tail
+// (shim + fatal log) WITHOUT
 // re-dispatching an event: reportError and listener-thrown errors have already
 // gone through JS dispatch, so dispatching again here would recurse.
 static void NativeReportFatalCallback(const FunctionCallbackInfo<Value>& info) {
@@ -23,40 +24,42 @@ static void NativeReportFatalCallback(const FunctionCallbackInfo<Value>& info) {
 }
 
 void ErrorEvents::Init(Local<Context> context) {
-  // WHATWG error-events layer, layered on top of the generic event primitives
-  // installed by Events::Init. Plain (module-free) script, strict inside the
-  // IIFE, ES5-ish so it never depends on other runtime extensions. The IIFE is
-  // invoked with two arguments — the internal EventTarget backing the global
-  // (so native dispatch survives app code overwriting globalThis.dispatchEvent)
-  // and the native nativeReportFatal(error, stack) function that runs the
-  // terminal tail — and returns three closures bound to that backing store.
-  // ErrorEvent/PromiseRejectionEvent subclass the Event captured off globalThis
-  // at init time, which runs before any user code.
+  // WHATWG error-events layer (internal/error-events.js), layered on top of
+  // the generic event primitives installed by Events::Init. The builtin
+  // receives — via its binding bag — the internal EventTarget backing the
+  // global (so native dispatch survives app code overwriting
+  // globalThis.dispatchEvent) and the native nativeReportFatal(error, stack)
+  // function that runs the terminal tail, and returns three closures bound to
+  // that backing store. ErrorEvent/PromiseRejectionEvent subclass the Event
+  // captured off globalThis at init time, which runs before any user code.
   Isolate* isolate = v8::Isolate::GetCurrent();
 
   auto cache = Caches::Get(isolate);
   tns::Assert(cache != nullptr && cache->GlobalEventTarget != nullptr, isolate);
   Local<Object> globalTarget = cache->GlobalEventTarget->Get(isolate);
 
-  Local<Value> result;
-  bool success = BuiltinLoader::RunBuiltin(context, BuiltinId::kErrorEvents)
-                     .ToLocal(&result);
-  tns::Assert(success && result->IsFunction(), isolate);
-
-  Local<v8::Function> iife = result.As<v8::Function>();
-
   Local<v8::Function> nativeReportFatal;
-  success = v8::Function::New(context, NativeReportFatalCallback)
-                .ToLocal(&nativeReportFatal);
+  bool success = v8::Function::New(context, NativeReportFatalCallback)
+                     .ToLocal(&nativeReportFatal);
   tns::Assert(success, isolate);
 
-  Local<Value> installArgs[] = {globalTarget, nativeReportFatal};
-  Local<Value> iifeResult;
-  success = iife->Call(context, context->Global(), 2, installArgs)
-                .ToLocal(&iifeResult);
-  tns::Assert(success && iifeResult->IsArray(), isolate);
+  Local<Object> binding = Object::New(isolate);
+  success =
+      binding
+          ->Set(context, tns::ToV8String(isolate, "globalTarget"), globalTarget)
+          .FromMaybe(false) &&
+      binding
+          ->Set(context, tns::ToV8String(isolate, "nativeReportFatal"),
+                nativeReportFatal)
+          .FromMaybe(false);
+  tns::Assert(success, isolate);
+
+  Local<Value> result;
+  success = BuiltinLoader::RunBuiltin(context, BuiltinId::kErrorEvents, binding)
+                .ToLocal(&result);
+  tns::Assert(success && result->IsArray(), isolate);
 
-  Local<v8::Array> closures = iifeResult.As<v8::Array>();
+  Local<v8::Array> closures = result.As<v8::Array>();
   Local<Value> errorFn, rejectionFn, handledFn;
   tns::Assert(
       closures->Get(context, 0).ToLocal(&errorFn) && errorFn->IsFunction(),
diff --git a/NativeScript/runtime/Events.cpp b/NativeScript/runtime/Events.cpp
index d75791b7..b07537d6 100644
--- a/NativeScript/runtime/Events.cpp
+++ b/NativeScript/runtime/Events.cpp
@@ -9,10 +9,9 @@ using namespace v8;
 namespace tns {
 
 void Events::Init(Local<Context> context) {
-  // Generic WHATWG event primitives. Plain (module-free) script, strict inside
-  // the IIFE, ES5-ish so it never depends on other runtime extensions. The IIFE
-  // installs Event/EventTarget and the global EventTarget methods, then returns
-  // the internal EventTarget instance backing the global so native dispatch
+  // Generic WHATWG event primitives (internal/events.js). The builtin installs
+  // Event/EventTarget and the global EventTarget methods, then returns the
+  // internal EventTarget instance backing the global so native dispatch
   // survives app code overwriting globalThis.dispatchEvent. The error-events
   // layer (ErrorEvents::Init) runs immediately after and installs the native
   // listener-error reporter through _installListenerErrorReporter.
@@ -21,18 +20,11 @@ void Events::Init(Local<Context> context) {
   Local<Value> result;
   bool success =
       BuiltinLoader::RunBuiltin(context, BuiltinId::kEvents).ToLocal(&result);
-  tns::Assert(success && result->IsFunction(), isolate);
-
-  Local<v8::Function> iife = result.As<v8::Function>();
-
-  Local<Value> iifeResult;
-  success =
-      iife->Call(context, context->Global(), 0, nullptr).ToLocal(&iifeResult);
-  tns::Assert(success && iifeResult->IsObject(), isolate);
+  tns::Assert(success && result->IsObject(), isolate);
 
   auto cache = Caches::Get(isolate);
-  cache->GlobalEventTarget = std::make_unique<Persistent<v8::Object>>(
-      isolate, iifeResult.As<Object>());
+  cache->GlobalEventTarget =
+      std::make_unique<Persistent<v8::Object>>(isolate, result.As<Object>());
 }
 
 }  // namespace tns
diff --git a/NativeScript/runtime/PromiseProxy.cpp b/NativeScript/runtime/PromiseProxy.cpp
index 6ac8c56a..b918245b 100644
--- a/NativeScript/runtime/PromiseProxy.cpp
+++ b/NativeScript/runtime/PromiseProxy.cpp
@@ -24,22 +24,22 @@ static void IsRuntimeRunloopCallback(const FunctionCallbackInfo<Value>& args) {
 void PromiseProxy::Init(v8::Local<v8::Context> context) {
   Isolate* isolate = v8::Isolate::GetCurrent();
 
-  Local<Value> result;
-  bool success = BuiltinLoader::RunBuiltin(context, BuiltinId::kPromiseProxy)
-                     .ToLocal(&result);
-  tns::Assert(success && result->IsFunction(), isolate);
-
-  Local<v8::Function> installProxy = result.As<v8::Function>();
-
   Local<v8::Function> isRuntimeRunloop;
-  success = v8::Function::New(context, IsRuntimeRunloopCallback)
-                .ToLocal(&isRuntimeRunloop);
+  bool success = v8::Function::New(context, IsRuntimeRunloopCallback)
+                     .ToLocal(&isRuntimeRunloop);
   tns::Assert(success, isolate);
 
-  Local<Value> installArgs[] = {isRuntimeRunloop};
-  Local<Value> installResult;
-  success = installProxy->Call(context, context->Global(), 1, installArgs)
-                .ToLocal(&installResult);
+  Local<Object> binding = Object::New(isolate);
+  success = binding
+                ->Set(context, tns::ToV8String(isolate, "isRuntimeRunloop"),
+                      isRuntimeRunloop)
+                .FromMaybe(false);
+  tns::Assert(success, isolate);
+
+  Local<Value> result;
+  success =
+      BuiltinLoader::RunBuiltin(context, BuiltinId::kPromiseProxy, binding)
+          .ToLocal(&result);
   tns::Assert(success, isolate);
 }
 
diff --git a/NativeScript/runtime/js/README.md b/NativeScript/runtime/js/README.md
new file mode 100644
index 00000000..3db4cdcf
--- /dev/null
+++ b/NativeScript/runtime/js/README.md
@@ -0,0 +1,37 @@
+# Runtime builtins
+
+The `.js` files in this directory are the runtime's internal JavaScript. At
+build time the "Generate RuntimeBuiltins" Xcode phase runs `tools/js2c.mjs`,
+which embeds them into `NativeScript/runtime/generated/RuntimeBuiltins.cpp`;
+at runtime `BuiltinLoader::RunBuiltin` compiles and executes them with an
+`internal/<name>.js` script origin and a process-wide bytecode cache.
+
+## Contract (Node's internalBinding idiom)
+
+Every file is compiled as a **function body** via `v8::ScriptCompiler::CompileFunction`
+with one fixed parameter:
+
+```js
+const { someNative, anotherNative } = binding;
+```
+
+- `binding` is a plain object of natives built by the C++ call site; a file
+  that needs nothing from C++ simply doesn't mention it.
+- Because the file is a function body, **top-level `return` is legal** — a
+  builtin's return value is what `RunBuiltin` hands back to C++ (used to
+  return factory functions and init results).
+- Strict mode is per-file: start the file with `"use strict";` to opt in.
+- Destructure `binding` once, at the top of the file, so the file's native
+  dependencies are visible and greppable.
+
+## Rules
+
+- Run at isolate init, before any user code: capture any global you rely on
+  (e.g. `globalThis.Event`) eagerly so later monkey-patching can't break you.
+- No `import`/`export` — these are classic function bodies, not modules.
+- ESLint (`eslint.config.mjs` at the repo root, run by lint-staged) declares
+  `binding` and the reachable native globals; `no-undef` is the typo net.
+  If a builtin starts using a new native global, add it there.
+- File names are kebab-case; the name determines the `BuiltinId` enum value
+  (`promise-proxy.js` → `kPromiseProxy`) and the script origin. New files must
+  also be added to `tools/js2c-inputs.xcfilelist`.
diff --git a/NativeScript/runtime/js/class-extends.js b/NativeScript/runtime/js/class-extends.js
index 40984f24..33a60cef 100644
--- a/NativeScript/runtime/js/class-extends.js
+++ b/NativeScript/runtime/js/class-extends.js
@@ -1,4 +1,3 @@
-(function() { 
     function __extends(d, b) { 
          for (var p in b) {
              if (b.hasOwnProperty(p)) {
@@ -10,4 +9,3 @@
 (__.prototype = b.prototype, new __());
     } 
     return __extends;
-})()
diff --git a/NativeScript/runtime/js/error-events.js b/NativeScript/runtime/js/error-events.js
index 13fe428b..f7f5eac3 100644
--- a/NativeScript/runtime/js/error-events.js
+++ b/NativeScript/runtime/js/error-events.js
@@ -1,81 +1,81 @@
-(function (globalTarget, nativeReportFatal) {
-  "use strict";
-  var g = globalThis;
-  var Event = g.Event;
+"use strict";
 
-  function ErrorEvent(type, opts) {
-    opts = opts || {};
-    Event.call(this, type, opts);
-    this.message = opts.message !== undefined ? String(opts.message) : "";
-    this.filename = opts.filename !== undefined ? String(opts.filename) : "";
-    this.lineno = opts.lineno !== undefined ? (opts.lineno | 0) : 0;
-    this.colno = opts.colno !== undefined ? (opts.colno | 0) : 0;
-    this.error = opts.error !== undefined ? opts.error : null;
-  }
-  ErrorEvent.prototype = Object.create(Event.prototype);
-  ErrorEvent.prototype.constructor = ErrorEvent;
-
-  function PromiseRejectionEvent(type, opts) {
-    opts = opts || {};
-    Event.call(this, type, opts);
-    this.promise = opts.promise;
-    this.reason = opts.reason;
-  }
-  PromiseRejectionEvent.prototype = Object.create(Event.prototype);
-  PromiseRejectionEvent.prototype.constructor = PromiseRejectionEvent;
+const { globalTarget, nativeReportFatal } = binding;
+var g = globalThis;
+var Event = g.Event;
 
-  // A listener that throws must not stop other listeners: route the thrown
-  // value to the native fatal tail instead of ever recursively dispatching
-  // another `error` event from inside dispatch.
-  globalTarget._installListenerErrorReporter(function (e) {
-    try { nativeReportFatal(e, (e && e.stack) || ""); } catch (ignored) {}
-  });
+function ErrorEvent(type, opts) {
+  opts = opts || {};
+  Event.call(this, type, opts);
+  this.message = opts.message !== undefined ? String(opts.message) : "";
+  this.filename = opts.filename !== undefined ? String(opts.filename) : "";
+  this.lineno = opts.lineno !== undefined ? (opts.lineno | 0) : 0;
+  this.colno = opts.colno !== undefined ? (opts.colno | 0) : 0;
+  this.error = opts.error !== undefined ? opts.error : null;
+}
+ErrorEvent.prototype = Object.create(Event.prototype);
+ErrorEvent.prototype.constructor = ErrorEvent;
 
-  g.reportError = function (e) {
-    if (arguments.length === 0) {
-      throw new TypeError("Failed to execute 'reportError': 1 argument required, but only 0 present.");
-    }
-    var ev = new ErrorEvent("error", {
-      message: (e && e.message !== undefined && e.message !== null) ? String(e.message) : String(e),
-      error: e,
-      cancelable: true
-    });
-    if (globalTarget.dispatchEvent(ev)) {
-      nativeReportFatal(e, (e && e.stack) || "");
-    }
-  };
+function PromiseRejectionEvent(type, opts) {
+  opts = opts || {};
+  Event.call(this, type, opts);
+  this.promise = opts.promise;
+  this.reason = opts.reason;
+}
+PromiseRejectionEvent.prototype = Object.create(Event.prototype);
+PromiseRejectionEvent.prototype.constructor = PromiseRejectionEvent;
 
-  g.ErrorEvent = ErrorEvent;
-  g.PromiseRejectionEvent = PromiseRejectionEvent;
+// A listener that throws must not stop other listeners: route the thrown
+// value to the native fatal tail instead of ever recursively dispatching
+// another `error` event from inside dispatch.
+globalTarget._installListenerErrorReporter(function (e) {
+  try { nativeReportFatal(e, (e && e.stack) || ""); } catch (ignored) {}
+});
 
-  // Closures called by C++. They never look up globalThis.dispatchEvent, so
-  // they keep working even if app code overwrites it.
-  function dispatchErrorEvent(error, message, stack) {
-    var ev = new ErrorEvent("error", {
-      message: message !== undefined && message !== null ? String(message) : "",
-      error: error,
-      cancelable: true
-    });
-    globalTarget.dispatchEvent(ev);
-    return ev.defaultPrevented;
-  }
-  function dispatchUnhandledRejection(promise, reason) {
-    var ev = new PromiseRejectionEvent("unhandledrejection", {
-      promise: promise,
-      reason: reason,
-      cancelable: true
-    });
-    globalTarget.dispatchEvent(ev);
-    return ev.defaultPrevented;
+g.reportError = function (e) {
+  if (arguments.length === 0) {
+    throw new TypeError("Failed to execute 'reportError': 1 argument required, but only 0 present.");
   }
-  function dispatchRejectionHandled(promise, reason) {
-    var ev = new PromiseRejectionEvent("rejectionhandled", {
-      promise: promise,
-      reason: reason,
-      cancelable: false
-    });
-    globalTarget.dispatchEvent(ev);
+  var ev = new ErrorEvent("error", {
+    message: (e && e.message !== undefined && e.message !== null) ? String(e.message) : String(e),
+    error: e,
+    cancelable: true
+  });
+  if (globalTarget.dispatchEvent(ev)) {
+    nativeReportFatal(e, (e && e.stack) || "");
   }
+};
+
+g.ErrorEvent = ErrorEvent;
+g.PromiseRejectionEvent = PromiseRejectionEvent;
+
+// Closures called by C++. They never look up globalThis.dispatchEvent, so
+// they keep working even if app code overwrites it.
+function dispatchErrorEvent(error, message, stack) {
+  var ev = new ErrorEvent("error", {
+    message: message !== undefined && message !== null ? String(message) : "",
+    error: error,
+    cancelable: true
+  });
+  globalTarget.dispatchEvent(ev);
+  return ev.defaultPrevented;
+}
+function dispatchUnhandledRejection(promise, reason) {
+  var ev = new PromiseRejectionEvent("unhandledrejection", {
+    promise: promise,
+    reason: reason,
+    cancelable: true
+  });
+  globalTarget.dispatchEvent(ev);
+  return ev.defaultPrevented;
+}
+function dispatchRejectionHandled(promise, reason) {
+  var ev = new PromiseRejectionEvent("rejectionhandled", {
+    promise: promise,
+    reason: reason,
+    cancelable: false
+  });
+  globalTarget.dispatchEvent(ev);
+}
 
-  return [dispatchErrorEvent, dispatchUnhandledRejection, dispatchRejectionHandled];
-})
+return [dispatchErrorEvent, dispatchUnhandledRejection, dispatchRejectionHandled];
diff --git a/NativeScript/runtime/js/events.js b/NativeScript/runtime/js/events.js
index 8cb1a78b..62f3212d 100644
--- a/NativeScript/runtime/js/events.js
+++ b/NativeScript/runtime/js/events.js
@@ -1,129 +1,127 @@
-(function () {
-  "use strict";
-  var g = globalThis;
+"use strict";
+var g = globalThis;
 
-  function Event(type, opts) {
-    opts = opts || {};
-    this.type = String(type);
-    this.bubbles = !!opts.bubbles;
-    this.cancelable = !!opts.cancelable;
-    this.composed = !!opts.composed;
-    this.defaultPrevented = false;
-    this.target = null;
-    this.currentTarget = null;
-    this._stopPropagation = false;
-    this._stopImmediate = false;
-  }
-  Event.prototype.preventDefault = function () {
-    if (this.cancelable) { this.defaultPrevented = true; }
-  };
-  Event.prototype.stopPropagation = function () { this._stopPropagation = true; };
-  Event.prototype.stopImmediatePropagation = function () {
-    this._stopPropagation = true;
-    this._stopImmediate = true;
-  };
+function Event(type, opts) {
+  opts = opts || {};
+  this.type = String(type);
+  this.bubbles = !!opts.bubbles;
+  this.cancelable = !!opts.cancelable;
+  this.composed = !!opts.composed;
+  this.defaultPrevented = false;
+  this.target = null;
+  this.currentTarget = null;
+  this._stopPropagation = false;
+  this._stopImmediate = false;
+}
+Event.prototype.preventDefault = function () {
+  if (this.cancelable) { this.defaultPrevented = true; }
+};
+Event.prototype.stopPropagation = function () { this._stopPropagation = true; };
+Event.prototype.stopImmediatePropagation = function () {
+  this._stopPropagation = true;
+  this._stopImmediate = true;
+};
 
-  // A listener that throws must not stop other listeners: route the thrown
-  // value to the native fatal tail instead of ever recursively dispatching
-  // another `error` event from inside dispatch. The error-events layer
-  // installs the real reporter via _installListenerErrorReporter (before any
-  // user code runs); until then a thrown listener is swallowed.
-  var reportListenerError = function (e) {};
+// A listener that throws must not stop other listeners: route the thrown
+// value to the native fatal tail instead of ever recursively dispatching
+// another `error` event from inside dispatch. The error-events layer
+// installs the real reporter via _installListenerErrorReporter (before any
+// user code runs); until then a thrown listener is swallowed.
+var reportListenerError = function (e) {};
 
-  function EventTargetImpl() { this._listeners = Object.create(null); }
-  EventTargetImpl.prototype.addEventListener = function (type, callback, options) {
-    if (callback === null || callback === undefined) { return; }
-    type = String(type);
-    var capture = false, once = false;
-    if (typeof options === "boolean") {
-      capture = options;
-    } else if (options && typeof options === "object") {
-      capture = !!options.capture;
-      once = !!options.once;
-    }
-    var list = this._listeners[type];
-    if (!list) { list = this._listeners[type] = []; }
-    for (var i = 0; i < list.length; i++) {
-      if (list[i].callback === callback && list[i].capture === capture) { return; }
-    }
-    list.push({ callback: callback, once: once, capture: capture });
-  };
-  EventTargetImpl.prototype.removeEventListener = function (type, callback, options) {
-    type = String(type);
-    var capture = false;
-    if (typeof options === "boolean") {
-      capture = options;
-    } else if (options && typeof options === "object") {
-      capture = !!options.capture;
-    }
-    var list = this._listeners[type];
-    if (!list) { return; }
-    for (var i = 0; i < list.length; i++) {
-      if (list[i].callback === callback && list[i].capture === capture) {
-        list.splice(i, 1);
-        return;
-      }
+function EventTargetImpl() { this._listeners = Object.create(null); }
+EventTargetImpl.prototype.addEventListener = function (type, callback, options) {
+  if (callback === null || callback === undefined) { return; }
+  type = String(type);
+  var capture = false, once = false;
+  if (typeof options === "boolean") {
+    capture = options;
+  } else if (options && typeof options === "object") {
+    capture = !!options.capture;
+    once = !!options.once;
+  }
+  var list = this._listeners[type];
+  if (!list) { list = this._listeners[type] = []; }
+  for (var i = 0; i < list.length; i++) {
+    if (list[i].callback === callback && list[i].capture === capture) { return; }
+  }
+  list.push({ callback: callback, once: once, capture: capture });
+};
+EventTargetImpl.prototype.removeEventListener = function (type, callback, options) {
+  type = String(type);
+  var capture = false;
+  if (typeof options === "boolean") {
+    capture = options;
+  } else if (options && typeof options === "object") {
+    capture = !!options.capture;
+  }
+  var list = this._listeners[type];
+  if (!list) { return; }
+  for (var i = 0; i < list.length; i++) {
+    if (list[i].callback === callback && list[i].capture === capture) {
+      list.splice(i, 1);
+      return;
     }
-  };
-  EventTargetImpl.prototype.dispatchEvent = function (event) {
-    event.target = this;
-    event.currentTarget = this;
-    var list = this._listeners[event.type];
-    if (list) {
-      // Snapshot so listeners added during dispatch are not invoked and
-      // registration order is preserved.
-      var snapshot = list.slice();
-      for (var i = 0; i < snapshot.length; i++) {
-        var entry = snapshot[i];
-        var idx = list.indexOf(entry);
-        if (idx === -1) { continue; }  // removed since snapshot
-        if (entry.once) { list.splice(idx, 1); }
-        var cb = entry.callback;
-        try {
-          if (typeof cb === "function") {
-            cb.call(this, event);
-          } else if (cb && typeof cb.handleEvent === "function") {
-            cb.handleEvent(event);
-          }
-        } catch (e) {
-          reportListenerError(e);
+  }
+};
+EventTargetImpl.prototype.dispatchEvent = function (event) {
+  event.target = this;
+  event.currentTarget = this;
+  var list = this._listeners[event.type];
+  if (list) {
+    // Snapshot so listeners added during dispatch are not invoked and
+    // registration order is preserved.
+    var snapshot = list.slice();
+    for (var i = 0; i < snapshot.length; i++) {
+      var entry = snapshot[i];
+      var idx = list.indexOf(entry);
+      if (idx === -1) { continue; }  // removed since snapshot
+      if (entry.once) { list.splice(idx, 1); }
+      var cb = entry.callback;
+      try {
+        if (typeof cb === "function") {
+          cb.call(this, event);
+        } else if (cb && typeof cb.handleEvent === "function") {
+          cb.handleEvent(event);
         }
-        if (event._stopImmediate) { break; }
+      } catch (e) {
+        reportListenerError(e);
       }
+      if (event._stopImmediate) { break; }
     }
-    event.currentTarget = null;
-    return !event.defaultPrevented;
-  };
+  }
+  event.currentTarget = null;
+  return !event.defaultPrevented;
+};
 
-  // Internal EventTarget instance backing the global. globalThis's prototype
-  // is intentionally NOT made an EventTarget; only the three methods are
-  // bound onto it.
-  var globalTarget = new EventTargetImpl();
-  // Called by the error-events layer to install the native listener-error
-  // reporter into this closure. One-shot: the backing target leaks to app
-  // code via event.target, so the hook removes itself after the install
-  // (which happens during runtime init, before any user code runs).
-  globalTarget._installListenerErrorReporter = function (fn) {
-    reportListenerError = fn;
-    delete globalTarget._installListenerErrorReporter;
-  };
-  g.addEventListener = function (type, callback, options) {
-    return globalTarget.addEventListener(type, callback, options);
-  };
-  g.removeEventListener = function (type, callback, options) {
-    return globalTarget.removeEventListener(type, callback, options);
-  };
-  g.dispatchEvent = function (event) {
-    return globalTarget.dispatchEvent(event);
-  };
+// Internal EventTarget instance backing the global. globalThis's prototype
+// is intentionally NOT made an EventTarget; only the three methods are
+// bound onto it.
+var globalTarget = new EventTargetImpl();
+// Called by the error-events layer to install the native listener-error
+// reporter into this closure. One-shot: the backing target leaks to app
+// code via event.target, so the hook removes itself after the install
+// (which happens during runtime init, before any user code runs).
+globalTarget._installListenerErrorReporter = function (fn) {
+  reportListenerError = fn;
+  delete globalTarget._installListenerErrorReporter;
+};
+g.addEventListener = function (type, callback, options) {
+  return globalTarget.addEventListener(type, callback, options);
+};
+g.removeEventListener = function (type, callback, options) {
+  return globalTarget.removeEventListener(type, callback, options);
+};
+g.dispatchEvent = function (event) {
+  return globalTarget.dispatchEvent(event);
+};
 
-  function EventTarget() { EventTargetImpl.call(this); }
-  EventTarget.prototype.addEventListener = EventTargetImpl.prototype.addEventListener;
-  EventTarget.prototype.removeEventListener = EventTargetImpl.prototype.removeEventListener;
-  EventTarget.prototype.dispatchEvent = EventTargetImpl.prototype.dispatchEvent;
+function EventTarget() { EventTargetImpl.call(this); }
+EventTarget.prototype.addEventListener = EventTargetImpl.prototype.addEventListener;
+EventTarget.prototype.removeEventListener = EventTargetImpl.prototype.removeEventListener;
+EventTarget.prototype.dispatchEvent = EventTargetImpl.prototype.dispatchEvent;
 
-  g.Event = Event;
-  g.EventTarget = EventTarget;
+g.Event = Event;
+g.EventTarget = EventTarget;
 
-  return globalTarget;
-})
+return globalTarget;
diff --git a/NativeScript/runtime/js/promise-proxy.js b/NativeScript/runtime/js/promise-proxy.js
index b88f0b73..091d127c 100644
--- a/NativeScript/runtime/js/promise-proxy.js
+++ b/NativeScript/runtime/js/promise-proxy.js
@@ -2,68 +2,68 @@
 // that thread is the runtime loop. A Promise created on a background
 // thread settles on whichever thread resolves it, because the background
 // run loop may be dormant and marshaling a resolution to it would hang.
-(function(isRuntimeRunloop) {
-    global.Promise = new Proxy(global.Promise, {
-        construct: function(target, args) {
-            let origFunc = args[0];
-            let runloop = CFRunLoopGetCurrent();
-            let originIsRuntimeLoop = isRuntimeRunloop();
+const { isRuntimeRunloop } = binding;
 
-            let promise = new target(function(resolve, reject) {
-                function isFulfilled() {
-                    return !resolve;
+global.Promise = new Proxy(global.Promise, {
+    construct: function(target, args) {
+        let origFunc = args[0];
+        let runloop = CFRunLoopGetCurrent();
+        let originIsRuntimeLoop = isRuntimeRunloop();
+
+        let promise = new target(function(resolve, reject) {
+            function isFulfilled() {
+                return !resolve;
+            }
+            function markFulfilled() {
+                origFunc = null;
+                resolve = null;
+                reject = null;
+            }
+            origFunc(value => {
+                if (isFulfilled()) {
+                    return;
                 }
-                function markFulfilled() {
-                    origFunc = null;
-                    resolve = null;
-                    reject = null;
+                const resolveCall = resolve.bind(this, value);
+                if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
+                    markFulfilled();
+                    resolveCall();
+                } else {
+                    CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, resolveCall);
+                    CFRunLoopWakeUp(runloop);
+                    markFulfilled();
+                }
+            }, reason => {
+                if (isFulfilled()) {
+                    return;
+                }
+                const rejectCall = reject.bind(this, reason);
+                if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
+                    markFulfilled();
+                    rejectCall();
+                } else {
+                    CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, rejectCall);
+                    CFRunLoopWakeUp(runloop);
+                    markFulfilled();
                 }
-                origFunc(value => {
-                    if (isFulfilled()) {
-                        return;
-                    }
-                    const resolveCall = resolve.bind(this, value);
-                    if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
-                        markFulfilled();
-                        resolveCall();
-                    } else {
-                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, resolveCall);
-                        CFRunLoopWakeUp(runloop);
-                        markFulfilled();
-                    }
-                }, reason => {
-                    if (isFulfilled()) {
-                        return;
-                    }
-                    const rejectCall = reject.bind(this, reason);
-                    if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
-                        markFulfilled();
-                        rejectCall();
-                    } else {
-                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, rejectCall);
-                        CFRunLoopWakeUp(runloop);
-                        markFulfilled();
-                    }
-                });
             });
+        });
 
-            return new Proxy(promise, {
-                get: function(target, name) {
-                    let orig = target[name];
-                    if (name === "then" || name === "catch" || name === "finally") {
-                        return orig.bind(target);
-                    }
-                    return typeof orig === 'function' ? function(x) {
-                        if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
-                            orig.bind(target, x)();
-                            return target;
-                        }
-                        CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, orig.bind(target, x));
-                        CFRunLoopWakeUp(runloop);
-                        return target;
-                    } : orig;
+        return new Proxy(promise, {
+            get: function(target, name) {
+                let orig = target[name];
+                if (name === "then" || name === "catch" || name === "finally") {
+                    return orig.bind(target);
                 }
-            });
-        }
-    });
-})
+                return typeof orig === 'function' ? function(x) {
+                    if (!originIsRuntimeLoop || runloop === CFRunLoopGetCurrent()) {
+                        orig.bind(target, x)();
+                        return target;
+                    }
+                    CFRunLoopPerformBlock(runloop, kCFRunLoopDefaultMode, orig.bind(target, x));
+                    CFRunLoopWakeUp(runloop);
+                    return target;
+                } : orig;
+            }
+        });
+    }
+});
diff --git a/NativeScript/runtime/js/require-factory.js b/NativeScript/runtime/js/require-factory.js
index af08aa5c..50691b2e 100644
--- a/NativeScript/runtime/js/require-factory.js
+++ b/NativeScript/runtime/js/require-factory.js
@@ -1,4 +1,3 @@
-(function() { 
     function require_factory(requireInternal, dirName) { 
         return function require(modulePath) { 
             if(global.__pauseOnNextRequire) {  debugger; 
@@ -7,4 +6,3 @@ global.__pauseOnNextRequire = false; }
         } 
     } 
     return require_factory; 
-})()
diff --git a/NativeScript/runtime/js/smart-stringify.js b/NativeScript/runtime/js/smart-stringify.js
index 0ff7f09d..5304d951 100644
--- a/NativeScript/runtime/js/smart-stringify.js
+++ b/NativeScript/runtime/js/smart-stringify.js
@@ -1,19 +1,17 @@
-(function () {
-    function smartStringify(object) {
-        const seen = [];
-        var replacer = function (key, value) {
-            if (value != null && typeof value == "object") {
-                if (seen.indexOf(value) >= 0) {
-                    if (key) {
-                        return "[Circular]";
-                    }
-                    return;
+function smartStringify(object) {
+    const seen = [];
+    var replacer = function (key, value) {
+        if (value != null && typeof value == "object") {
+            if (seen.indexOf(value) >= 0) {
+                if (key) {
+                    return "[Circular]";
                 }
-                seen.push(value);
+                return;
             }
-            return value;
-        };
-        return JSON.stringify(object, replacer, 2);
-    }
-    return smartStringify;
-})();
+            seen.push(value);
+        }
+        return value;
+    };
+    return JSON.stringify(object, replacer, 2);
+}
+return smartStringify;
diff --git a/NativeScript/runtime/js/ts-helpers.js b/NativeScript/runtime/js/ts-helpers.js
index 38d43820..bd3cbc8d 100644
--- a/NativeScript/runtime/js/ts-helpers.js
+++ b/NativeScript/runtime/js/ts-helpers.js
@@ -1,107 +1,105 @@
-(() => {
-    var __originalExtends = global.__extends;
-    var __extends = (Child, Parent) => {
-        var extendingNativeClass = !!Parent.extend && (Parent.extend.toString().indexOf("[native code]") > -1);
-        if (!extendingNativeClass) {
-            __extends_ts(Child, Parent);
-            return;
-        }
+var __originalExtends = global.__extends;
+var __extends = (Child, Parent) => {
+    var extendingNativeClass = !!Parent.extend && (Parent.extend.toString().indexOf("[native code]") > -1);
+    if (!extendingNativeClass) {
+        __extends_ts(Child, Parent);
+        return;
+    }
 
-        if (Parent.__isPrototypeImplementationObject) {
-            throw new Error("Can not extend an already extended native object.");
-        }
+    if (Parent.__isPrototypeImplementationObject) {
+        throw new Error("Can not extend an already extended native object.");
+    }
 
-        function extend(thiz) {
-            var child = thiz.__proto__.__child;
-            if (!child.__extended) {
-                var parent = thiz.__proto__.__parent;
-                child.__extended = parent.extend(child.prototype, {
-                    name: child.name,
-                    protocols: child.ObjCProtocols || [],
-                    exposedMethods: child.ObjCExposedMethods || {}
-                });
-                child[Symbol.hasInstance] = function (instance) {
-                    return instance instanceof this.__extended;
-                }
+    function extend(thiz) {
+        var child = thiz.__proto__.__child;
+        if (!child.__extended) {
+            var parent = thiz.__proto__.__parent;
+            child.__extended = parent.extend(child.prototype, {
+                name: child.name,
+                protocols: child.ObjCProtocols || [],
+                exposedMethods: child.ObjCExposedMethods || {}
+            });
+            child[Symbol.hasInstance] = function (instance) {
+                return instance instanceof this.__extended;
             }
-            return child.__extended;
         }
+        return child.__extended;
+    }
 
-        Parent.call = function (thiz) {
-            var Extended = extend(thiz);
-            thiz.__container__ = true;
-            if (arguments.length > 1) {
-                thiz.__proto__ = new (Function.prototype.bind.apply(Extended, [null].concat(Array.prototype.slice.call(arguments, 1))));
-            } else {
-                thiz.__proto__ = new Extended()
-            }
-            return thiz.__proto__;
-        };
-
-        Parent.apply = function (thiz, args) {
-            var Extended = extend(thiz);
-            thiz.__container__ = true;
-            if (args && args.length > 0) {
-                thiz.__proto__ = new (Function.prototype.bind.apply(Extended, [null].concat(args)));
-            } else {
-                thiz.__proto__ = new Extended();
-            }
-            return thiz.__proto__;
-        };
-
-        __extends_ns(Child, Parent);
-        Child.__isPrototypeImplementationObject = true;
-        Child.__proto__ = Parent;
-        Child.prototype.__parent = Parent;
-        Child.prototype.__child = Child;
-
-        if (__originalExtends) {
-            __originalExtends(Child, Parent);
+    Parent.call = function (thiz) {
+        var Extended = extend(thiz);
+        thiz.__container__ = true;
+        if (arguments.length > 1) {
+            thiz.__proto__ = new (Function.prototype.bind.apply(Extended, [null].concat(Array.prototype.slice.call(arguments, 1))));
+        } else {
+            thiz.__proto__ = new Extended()
         }
+        return thiz.__proto__;
     };
 
-    var __extends_ts = function (child, parent) {
-        extendStaticFunctions(child, parent);
-        assignPrototypeFromParentToChild(parent, child);
+    Parent.apply = function (thiz, args) {
+        var Extended = extend(thiz);
+        thiz.__container__ = true;
+        if (args && args.length > 0) {
+            thiz.__proto__ = new (Function.prototype.bind.apply(Extended, [null].concat(args)));
+        } else {
+            thiz.__proto__ = new Extended();
+        }
+        return thiz.__proto__;
     };
 
-    var __extends_ns = function (child, parent) {
-        if (!parent.extend) {
-            assignPropertiesFromParentToChild(parent, child);
-        }
+    __extends_ns(Child, Parent);
+    Child.__isPrototypeImplementationObject = true;
+    Child.__proto__ = Parent;
+    Child.prototype.__parent = Parent;
+    Child.prototype.__child = Child;
 
-        assignPrototypeFromParentToChild(parent, child);
-    };
+    if (__originalExtends) {
+        __originalExtends(Child, Parent);
+    }
+};
 
-    var extendStaticFunctions =
-        Object.setPrototypeOf
-        || (hasInternalProtoProperty() && function (child, parent) { child.__proto__ = parent; })
-        || assignPropertiesFromParentToChild;
+var __extends_ts = function (child, parent) {
+    extendStaticFunctions(child, parent);
+    assignPrototypeFromParentToChild(parent, child);
+};
 
-    function hasInternalProtoProperty() {
-        return { __proto__: [] } instanceof Array;
+var __extends_ns = function (child, parent) {
+    if (!parent.extend) {
+        assignPropertiesFromParentToChild(parent, child);
     }
 
-    function assignPropertiesFromParentToChild(parent, child) {
-        for (var property in parent) {
-            if (parent.hasOwnProperty(property)) {
-                child[property] = parent[property];
-            }
+    assignPrototypeFromParentToChild(parent, child);
+};
+
+var extendStaticFunctions =
+    Object.setPrototypeOf
+    || (hasInternalProtoProperty() && function (child, parent) { child.__proto__ = parent; })
+    || assignPropertiesFromParentToChild;
+
+function hasInternalProtoProperty() {
+    return { __proto__: [] } instanceof Array;
+}
+
+function assignPropertiesFromParentToChild(parent, child) {
+    for (var property in parent) {
+        if (parent.hasOwnProperty(property)) {
+            child[property] = parent[property];
         }
     }
+}
 
-    function assignPrototypeFromParentToChild(parent, child) {
-        function __() {
-            this.constructor = child;
-        }
+function assignPrototypeFromParentToChild(parent, child) {
+    function __() {
+        this.constructor = child;
+    }
 
-        if (parent === null) {
-            child.prototype = Object.create(null);
-        } else {
-            __.prototype = parent.prototype;
-            child.prototype = new __();
-        }
+    if (parent === null) {
+        child.prototype = Object.create(null);
+    } else {
+        __.prototype = parent.prototype;
+        child.prototype = new __();
     }
+}
 
-    Object.defineProperty(global, "__extends", { value: __extends, writable: false });
-})()
+Object.defineProperty(global, "__extends", { value: __extends, writable: false });
diff --git a/eslint.config.mjs b/eslint.config.mjs
new file mode 100644
index 00000000..d4d540dc
--- /dev/null
+++ b/eslint.config.mjs
@@ -0,0 +1,47 @@
+// Lint setup for the runtime's builtin JavaScript (NativeScript/runtime/js).
+// Each file is compiled by BuiltinLoader as a FUNCTION BODY with the single
+// fixed parameter `binding` (see NativeScript/runtime/js/README.md), so
+// sourceType is "commonjs" (allows top-level return) and `binding` is a
+// declared global. no-undef is the typo net for binding-bag destructures and
+// native-global usage alike.
+import globals from 'globals';
+
+export default [
+  {
+    files: ['NativeScript/runtime/js/**/*.js'],
+    languageOptions: {
+      ecmaVersion: 2022,
+      sourceType: 'commonjs',
+      globals: {
+        ...globals.es2021,
+        binding: 'readonly',
+        global: 'readonly',
+        console: 'readonly',
+        URL: 'readonly',
+        URLSearchParams: 'readonly',
+        Blob: 'readonly',
+        File: 'readonly',
+        // Native globals resolved through the metadata interceptor at runtime:
+        interop: 'readonly',
+        NSUUID: 'readonly',
+        CGPoint: 'readonly',
+        CGRect: 'readonly',
+        CGSize: 'readonly',
+        UIEdgeInsets: 'readonly',
+        NSRange: 'readonly',
+        CFRunLoopGetCurrent: 'readonly',
+        CFRunLoopPerformBlock: 'readonly',
+        CFRunLoopWakeUp: 'readonly',
+        kCFRunLoopDefaultMode: 'readonly',
+        // Installed onto the global by inline-functions.js itself and
+        // referenced by bare name from its sibling decorators:
+        ObjCClass: 'readonly',
+        ObjCMethod: 'readonly',
+      },
+    },
+    rules: {
+      'no-undef': 'error',
+      'no-unused-vars': ['error', { args: 'none', caughtErrors: 'none' }],
+    },
+  },
+];
diff --git a/package.json b/package.json
index 48485134..d04235c7 100644
--- a/package.json
+++ b/package.json
@@ -34,6 +34,8 @@
     "conventional-changelog-cli": "^2.1.1",
     "dayjs": "^1.11.7",
     "esbuild": "0.28.1",
+    "eslint": "10.8.0",
+    "globals": "17.8.0",
     "husky": "^9.0.11",
     "lint-staged": "^15.2.7",
     "semver": "^7.5.0"
@@ -41,6 +43,9 @@
   "lint-staged": {
     "{NativeScript,metadata-generator/src,TestFixtures}/**/*.{h,hpp,c,cpp,mm,m}": [
       "clang-format -i"
+    ],
+    "NativeScript/runtime/js/**/*.js": [
+      "eslint"
     ]
   }
 }

From a56b0d429c864c9441540bf625bd8c4614010a32 Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@gmail.com>
Date: Thu, 30 Jul 2026 10:14:33 -0300
Subject: [PATCH 4/5] fix: harden builtin failure paths flagged in review

The enum-evaluation branch in Interop::WriteValue could dereference an
empty handle when Run failed (the && !result.IsEmpty() condition
suppressed the assert); WeakRef::Init and GetSmartJSONStringifyFunction
now log the caught exception before asserting so a builtin failure is
diagnosable; js2c gains --filelist, wired into the build phase, so a
builtin missing from js2c-inputs.xcfilelist fails the build instead of
being silently skipped by incremental change detection.
---
 NativeScript/runtime/Helpers.mm            |  4 +++
 NativeScript/runtime/Interop.mm            |  2 +-
 NativeScript/runtime/WeakRef.cpp           |  4 +++
 NativeScript/runtime/js/README.md          |  5 +++-
 NativeScript/runtime/js/require-factory.js | 18 ++++++------
 tools/js2c.mjs                             | 32 +++++++++++++++++++---
 v8ios.xcodeproj/project.pbxproj            |  2 +-
 7 files changed, 52 insertions(+), 15 deletions(-)

diff --git a/NativeScript/runtime/Helpers.mm b/NativeScript/runtime/Helpers.mm
index 5328e39a..64f47fb8 100644
--- a/NativeScript/runtime/Helpers.mm
+++ b/NativeScript/runtime/Helpers.mm
@@ -494,8 +494,12 @@
 
   Local<Context> context = isolate->GetCurrentContext();
 
+  TryCatch tc(isolate);
   Local<Value> result;
   bool success = BuiltinLoader::RunBuiltin(context, BuiltinId::kSmartStringify).ToLocal(&result);
+  if (!success && tc.HasCaught()) {
+    tns::LogError(isolate, tc);
+  }
   tns::Assert(success, isolate);
 
   if (result.IsEmpty() || !result->IsFunction()) {
diff --git a/NativeScript/runtime/Interop.mm b/NativeScript/runtime/Interop.mm
index 088f8f6c..1db2c19f 100644
--- a/NativeScript/runtime/Interop.mm
+++ b/NativeScript/runtime/Interop.mm
@@ -628,7 +628,7 @@ inline bool isBool() {
           tns::Assert(!script.IsEmpty(), isolate);
 
           Local<Value> result;
-          if (!script->Run(context).ToLocal(&result) && !result.IsEmpty()) {
+          if (!script->Run(context).ToLocal(&result)) {
             tns::Assert(false, isolate);
           }
 
diff --git a/NativeScript/runtime/WeakRef.cpp b/NativeScript/runtime/WeakRef.cpp
index 9796f4a3..de04d3ac 100644
--- a/NativeScript/runtime/WeakRef.cpp
+++ b/NativeScript/runtime/WeakRef.cpp
@@ -10,9 +10,13 @@ namespace tns {
 void WeakRef::Init(Local<Context> context) {
   Isolate* isolate = v8::Isolate::GetCurrent();
 
+  TryCatch tc(isolate);
   Local<Value> result;
   bool success =
       BuiltinLoader::RunBuiltin(context, BuiltinId::kWeakRef).ToLocal(&result);
+  if (!success && tc.HasCaught()) {
+    tns::LogError(isolate, tc);
+  }
   tns::Assert(success, isolate);
 }
 
diff --git a/NativeScript/runtime/js/README.md b/NativeScript/runtime/js/README.md
index 3db4cdcf..b4c251d7 100644
--- a/NativeScript/runtime/js/README.md
+++ b/NativeScript/runtime/js/README.md
@@ -28,10 +28,13 @@ const { someNative, anotherNative } = binding;
 
 - Run at isolate init, before any user code: capture any global you rely on
   (e.g. `globalThis.Event`) eagerly so later monkey-patching can't break you.
+  (Planned: a frozen `primordials` namespace as a second fixed parameter,
+  Node-style, to make this systematic for closures that outlive init.)
 - No `import`/`export` — these are classic function bodies, not modules.
 - ESLint (`eslint.config.mjs` at the repo root, run by lint-staged) declares
   `binding` and the reachable native globals; `no-undef` is the typo net.
   If a builtin starts using a new native global, add it there.
 - File names are kebab-case; the name determines the `BuiltinId` enum value
   (`promise-proxy.js` → `kPromiseProxy`) and the script origin. New files must
-  also be added to `tools/js2c-inputs.xcfilelist`.
+  also be added to `tools/js2c-inputs.xcfilelist` — the build fails with an
+  explicit message if that list drifts out of sync (`js2c.mjs --filelist`).
diff --git a/NativeScript/runtime/js/require-factory.js b/NativeScript/runtime/js/require-factory.js
index 50691b2e..6c7fb761 100644
--- a/NativeScript/runtime/js/require-factory.js
+++ b/NativeScript/runtime/js/require-factory.js
@@ -1,8 +1,10 @@
-    function require_factory(requireInternal, dirName) { 
-        return function require(modulePath) { 
-            if(global.__pauseOnNextRequire) {  debugger; 
-global.__pauseOnNextRequire = false; }
-            return requireInternal(modulePath, dirName); 
-        } 
-    } 
-    return require_factory; 
+function require_factory(requireInternal, dirName) {
+    return function require(modulePath) {
+        if (global.__pauseOnNextRequire) {
+            debugger;
+            global.__pauseOnNextRequire = false;
+        }
+        return requireInternal(modulePath, dirName);
+    };
+}
+return require_factory;
diff --git a/tools/js2c.mjs b/tools/js2c.mjs
index 7c9cd3e6..ef8c97c0 100644
--- a/tools/js2c.mjs
+++ b/tools/js2c.mjs
@@ -6,16 +6,21 @@ import { readFileSync, writeFileSync, mkdirSync, existsSync } from 'node:fs';
 import { basename, join } from 'node:path';
 import { parseArgs } from 'node:util';
 
-const USAGE = `usage: node tools/js2c.mjs --out-dir <dir> [--minify] <file.js>...
+const USAGE = `usage: node tools/js2c.mjs --out-dir <dir> [--minify] [--filelist <xcfilelist>] <file.js>...
 
 Generates <dir>/RuntimeBuiltins.h and <dir>/RuntimeBuiltins.cpp from the given
 builtin JavaScript sources. Builtin ids and script-origin names derive from the
 file names (promise-proxy.js -> BuiltinId::kPromiseProxy, "internal/promise-proxy.js").
 
 options:
-  --out-dir <dir>  output directory for the generated files (required)
-  --minify         minify sources with esbuild (whitespace + syntax only)
-  --help           show this message`;
+  --out-dir <dir>        output directory for the generated files (required)
+  --minify               minify sources with esbuild (whitespace + syntax only)
+  --filelist <file>      xcfilelist whose .js entries must exactly match the
+                         inputs; drift fails the build (Xcode's incremental
+                         change detection reads the xcfilelist, so a new
+                         builtin missing from it would otherwise be skipped
+                         silently on incremental builds)
+  --help                 show this message`;
 
 let args;
 try {
@@ -23,6 +28,7 @@ try {
     options: {
       'out-dir': { type: 'string' },
       minify: { type: 'boolean', default: false },
+      filelist: { type: 'string' },
       help: { type: 'boolean', default: false },
     },
     allowPositionals: true,
@@ -47,6 +53,24 @@ if (!outDir || inputs.length === 0) {
 // Stable ordering regardless of shell glob order, so output never churns.
 inputs.sort((a, b) => basename(a).localeCompare(basename(b)));
 
+if (args.values.filelist) {
+  const listed = readFileSync(args.values.filelist, 'utf8')
+    .split('\n')
+    .map((l) => l.trim())
+    .filter((l) => l.endsWith('.js'))
+    .map((l) => basename(l))
+    .sort();
+  const actual = inputs.map((f) => basename(f)).sort();
+  if (JSON.stringify(listed) !== JSON.stringify(actual)) {
+    const missing = actual.filter((f) => !listed.includes(f));
+    const stale = listed.filter((f) => !actual.includes(f));
+    console.error(`error: ${args.values.filelist} is out of sync with the input files`);
+    if (missing.length) console.error(`  add:    ${missing.join(', ')}`);
+    if (stale.length) console.error(`  remove: ${stale.join(', ')}`);
+    process.exit(1);
+  }
+}
+
 const builtins = [];
 for (const file of inputs) {
   if (!existsSync(file)) {
diff --git a/v8ios.xcodeproj/project.pbxproj b/v8ios.xcodeproj/project.pbxproj
index 31f7e20a..ca428152 100644
--- a/v8ios.xcodeproj/project.pbxproj
+++ b/v8ios.xcodeproj/project.pbxproj
@@ -1970,7 +1970,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "set -e\nexport PATH=\"$PATH:/opt/homebrew/bin:/usr/local/bin\"\nif ! command -v node >/dev/null 2>&1; then\n  echo \"error: node is required to generate the runtime builtins (tools/js2c.mjs); install Node.js or add it to PATH\" >&2\n  exit 1\nfi\ncd \"${SRCROOT}\"\nnode tools/js2c.mjs --out-dir NativeScript/runtime/generated NativeScript/runtime/js/*.js\n";
+			shellScript = "set -e\nexport PATH=\"$PATH:/opt/homebrew/bin:/usr/local/bin\"\nif ! command -v node >/dev/null 2>&1; then\n  echo \"error: node is required to generate the runtime builtins (tools/js2c.mjs); install Node.js or add it to PATH\" >&2\n  exit 1\nfi\ncd \"${SRCROOT}\"\nnode tools/js2c.mjs --out-dir NativeScript/runtime/generated --filelist tools/js2c-inputs.xcfilelist NativeScript/runtime/js/*.js\n";
 		};
 		2BFE21F02AC1B28000307752 /* Add default metadata */ = {
 			isa = PBXShellScriptBuildPhase;

From 4b29896474683425078b78f7accfcb37776673e6 Mon Sep 17 00:00:00 2001
From: Eduardo Speroni <edusperoni@gmail.com>
Date: Thu, 30 Jul 2026 14:32:36 -0300
Subject: [PATCH 5/5] refactor: export builtins via module.exports instead of
 top-level return

Builtins are compiled as function bodies, so top-level `return` worked as the
export channel -- but it makes every builtin invalid JavaScript to any tool
that does not read this repo's ESLint config (editor TS servers, prettier,
review bots), for no gain.

BuiltinLoader now seeds Node's module wrapper (`exports`, `module`, `binding`),
ignores the call's return value and hands `module.exports` back to the C++ call
site, so both CommonJS export styles work and the files parse everywhere.
---
 NativeScript/runtime/BuiltinLoader.cpp     | 39 ++++++++++++++++------
 NativeScript/runtime/BuiltinLoader.h       |  9 ++---
 NativeScript/runtime/Events.cpp            |  2 +-
 NativeScript/runtime/js/README.md          | 21 ++++++++----
 NativeScript/runtime/js/class-extends.js   |  2 +-
 NativeScript/runtime/js/error-events.js    |  2 +-
 NativeScript/runtime/js/events.js          |  2 +-
 NativeScript/runtime/js/require-factory.js |  2 +-
 NativeScript/runtime/js/smart-stringify.js |  2 +-
 eslint.config.mjs                          | 14 ++++----
 10 files changed, 62 insertions(+), 33 deletions(-)

diff --git a/NativeScript/runtime/BuiltinLoader.cpp b/NativeScript/runtime/BuiltinLoader.cpp
index c3c5f4d5..d004db84 100644
--- a/NativeScript/runtime/BuiltinLoader.cpp
+++ b/NativeScript/runtime/BuiltinLoader.cpp
@@ -15,10 +15,14 @@ namespace {
 std::mutex builtinCacheMutex;
 std::vector<uint8_t> builtinCache[static_cast<unsigned>(BuiltinId::kCount)];
 
-// Every builtin is compiled as a function body receiving this single, fixed
-// parameter (Node's internalBinding idiom): natives arrive as properties of
-// one bag object and each file destructures what it needs.
+// Every builtin is compiled as a function body receiving these fixed
+// parameters, mirroring Node's module wrapper: a file exports through
+// `module.exports`/`exports`, and natives arrive as properties of the
+// `binding` bag (Node's internalBinding idiom) for each file to destructure.
+constexpr const char* kExportsParamName = "exports";
+constexpr const char* kModuleParamName = "module";
 constexpr const char* kBindingParamName = "binding";
+constexpr int kParamCount = 3;
 
 MaybeLocal<v8::Function> CompileBuiltin(Local<Context> context, BuiltinId id) {
   Isolate* isolate = v8::Isolate::GetCurrent();
@@ -45,7 +49,9 @@ MaybeLocal<v8::Function> CompileBuiltin(Local<Context> context, BuiltinId id) {
   );
   Local<v8::String> sourceText = tns::ToV8String(
       isolate, builtin.source, static_cast<int>(builtin.length));
-  Local<v8::String> params[] = {tns::ToV8String(isolate, kBindingParamName)};
+  Local<v8::String> params[] = {tns::ToV8String(isolate, kExportsParamName),
+                                tns::ToV8String(isolate, kModuleParamName),
+                                tns::ToV8String(isolate, kBindingParamName)};
 
   Local<v8::Function> fn;
   if (!blob.empty()) {
@@ -55,7 +61,8 @@ MaybeLocal<v8::Function> CompileBuiltin(Local<Context> context, BuiltinId id) {
         blob.data(), static_cast<int>(blob.size()),
         ScriptCompiler::CachedData::BufferNotOwned);
     ScriptCompiler::Source source(sourceText, origin, cachedData);
-    if (ScriptCompiler::CompileFunction(context, &source, 1, params, 0, nullptr,
+    if (ScriptCompiler::CompileFunction(context, &source, kParamCount, params,
+                                        0, nullptr,
                                         ScriptCompiler::kConsumeCodeCache)
             .ToLocal(&fn) &&
         !cachedData->rejected) {
@@ -66,8 +73,8 @@ MaybeLocal<v8::Function> CompileBuiltin(Local<Context> context, BuiltinId id) {
   }
 
   ScriptCompiler::Source source(sourceText, origin);
-  if (!ScriptCompiler::CompileFunction(context, &source, 1, params, 0, nullptr,
-                                       ScriptCompiler::kEagerCompile)
+  if (!ScriptCompiler::CompileFunction(context, &source, kParamCount, params, 0,
+                                       nullptr, ScriptCompiler::kEagerCompile)
            .ToLocal(&fn)) {
     return MaybeLocal<v8::Function>();
   }
@@ -96,9 +103,21 @@ MaybeLocal<Value> BuiltinLoader::RunBuiltin(Local<Context> context,
     return MaybeLocal<Value>();
   }
 
-  Local<Value> args[] = {binding.IsEmpty() ? v8::Undefined(isolate).As<Value>()
-                                           : binding};
-  return fn->Call(context, v8::Undefined(isolate), 1, args);
+  Local<Object> exportsObj = Object::New(isolate);
+  Local<Object> moduleObj = Object::New(isolate);
+  Local<v8::String> exportsKey = tns::ToV8String(isolate, kExportsParamName);
+  if (!moduleObj->Set(context, exportsKey, exportsObj).FromMaybe(false)) {
+    return MaybeLocal<Value>();
+  }
+
+  Local<Value> args[] = {
+      exportsObj, moduleObj,
+      binding.IsEmpty() ? v8::Undefined(isolate).As<Value>() : binding};
+  if (fn->Call(context, v8::Undefined(isolate), kParamCount, args).IsEmpty()) {
+    return MaybeLocal<Value>();
+  }
+
+  return moduleObj->Get(context, exportsKey);
 }
 
 }  // namespace tns
diff --git a/NativeScript/runtime/BuiltinLoader.h b/NativeScript/runtime/BuiltinLoader.h
index 7205a81e..453c3fa7 100644
--- a/NativeScript/runtime/BuiltinLoader.h
+++ b/NativeScript/runtime/BuiltinLoader.h
@@ -8,10 +8,11 @@ namespace tns {
 
 class BuiltinLoader {
  public:
-  // Compiles the builtin identified by id as a function body with the single
-  // fixed parameter `binding` (Node's internalBinding idiom), calls it with
-  // the given bag of natives (or undefined when omitted), and returns its
-  // return value. Scripts carry an "internal/<name>.js" origin so runtime
+  // Compiles the builtin identified by id as a function body with the fixed
+  // parameters `exports`, `module` and `binding` (Node's module wrapper plus
+  // its internalBinding idiom), calls it with the given bag of natives (or
+  // undefined when omitted), and returns the resulting `module.exports`.
+  // Scripts carry an "internal/<name>.js" origin so runtime
   // frames are identifiable in stack traces. Compilation goes through a
   // process-wide bytecode cache: the first run in the process compiles
   // eagerly and populates the cache, later isolates (workers) consume it
diff --git a/NativeScript/runtime/Events.cpp b/NativeScript/runtime/Events.cpp
index b07537d6..d92d2bbb 100644
--- a/NativeScript/runtime/Events.cpp
+++ b/NativeScript/runtime/Events.cpp
@@ -10,7 +10,7 @@ namespace tns {
 
 void Events::Init(Local<Context> context) {
   // Generic WHATWG event primitives (internal/events.js). The builtin installs
-  // Event/EventTarget and the global EventTarget methods, then returns the
+  // Event/EventTarget and the global EventTarget methods, then exports the
   // internal EventTarget instance backing the global so native dispatch
   // survives app code overwriting globalThis.dispatchEvent. The error-events
   // layer (ErrorEvents::Init) runs immediately after and installs the native
diff --git a/NativeScript/runtime/js/README.md b/NativeScript/runtime/js/README.md
index b4c251d7..0df07307 100644
--- a/NativeScript/runtime/js/README.md
+++ b/NativeScript/runtime/js/README.md
@@ -6,20 +6,27 @@ which embeds them into `NativeScript/runtime/generated/RuntimeBuiltins.cpp`;
 at runtime `BuiltinLoader::RunBuiltin` compiles and executes them with an
 `internal/<name>.js` script origin and a process-wide bytecode cache.
 
-## Contract (Node's internalBinding idiom)
+## Contract (Node's module wrapper + internalBinding idiom)
 
 Every file is compiled as a **function body** via `v8::ScriptCompiler::CompileFunction`
-with one fixed parameter:
+with the fixed parameters `exports`, `module` and `binding`:
 
 ```js
 const { someNative, anotherNative } = binding;
+
+module.exports = somethingTheCallSiteNeeds;
 ```
 
 - `binding` is a plain object of natives built by the C++ call site; a file
   that needs nothing from C++ simply doesn't mention it.
-- Because the file is a function body, **top-level `return` is legal** — a
-  builtin's return value is what `RunBuiltin` hands back to C++ (used to
-  return factory functions and init results).
+- **`module.exports` is the export channel** — whatever it holds when the file
+  finishes is what `RunBuiltin` hands back to C++ (used for factory functions
+  and init results). Both CommonJS styles work: replace the whole export with
+  `module.exports = x`, or hang properties off `exports`. A file that only
+  installs globals exports nothing and the call site ignores the value.
+- **No top-level `return`.** It would work — these are function bodies — but
+  every tool that isn't reading this repo's ESLint config (editors' TS server,
+  prettier, review bots) rejects the file as invalid JavaScript.
 - Strict mode is per-file: start the file with `"use strict";` to opt in.
 - Destructure `binding` once, at the top of the file, so the file's native
   dependencies are visible and greppable.
@@ -32,8 +39,8 @@ const { someNative, anotherNative } = binding;
   Node-style, to make this systematic for closures that outlive init.)
 - No `import`/`export` — these are classic function bodies, not modules.
 - ESLint (`eslint.config.mjs` at the repo root, run by lint-staged) declares
-  `binding` and the reachable native globals; `no-undef` is the typo net.
-  If a builtin starts using a new native global, add it there.
+  `exports`, `module`, `binding` and the reachable native globals; `no-undef`
+  is the typo net. If a builtin starts using a new native global, add it there.
 - File names are kebab-case; the name determines the `BuiltinId` enum value
   (`promise-proxy.js` → `kPromiseProxy`) and the script origin. New files must
   also be added to `tools/js2c-inputs.xcfilelist` — the build fails with an
diff --git a/NativeScript/runtime/js/class-extends.js b/NativeScript/runtime/js/class-extends.js
index 33a60cef..24e1f411 100644
--- a/NativeScript/runtime/js/class-extends.js
+++ b/NativeScript/runtime/js/class-extends.js
@@ -8,4 +8,4 @@
          d.prototype = b === null ? Object.create(b) : 
 (__.prototype = b.prototype, new __());
     } 
-    return __extends;
+    module.exports = __extends;
diff --git a/NativeScript/runtime/js/error-events.js b/NativeScript/runtime/js/error-events.js
index f7f5eac3..b530e0f2 100644
--- a/NativeScript/runtime/js/error-events.js
+++ b/NativeScript/runtime/js/error-events.js
@@ -78,4 +78,4 @@ function dispatchRejectionHandled(promise, reason) {
   globalTarget.dispatchEvent(ev);
 }
 
-return [dispatchErrorEvent, dispatchUnhandledRejection, dispatchRejectionHandled];
+module.exports = [dispatchErrorEvent, dispatchUnhandledRejection, dispatchRejectionHandled];
diff --git a/NativeScript/runtime/js/events.js b/NativeScript/runtime/js/events.js
index 62f3212d..612f3570 100644
--- a/NativeScript/runtime/js/events.js
+++ b/NativeScript/runtime/js/events.js
@@ -124,4 +124,4 @@ EventTarget.prototype.dispatchEvent = EventTargetImpl.prototype.dispatchEvent;
 g.Event = Event;
 g.EventTarget = EventTarget;
 
-return globalTarget;
+module.exports = globalTarget;
diff --git a/NativeScript/runtime/js/require-factory.js b/NativeScript/runtime/js/require-factory.js
index 6c7fb761..836bcf46 100644
--- a/NativeScript/runtime/js/require-factory.js
+++ b/NativeScript/runtime/js/require-factory.js
@@ -7,4 +7,4 @@ function require_factory(requireInternal, dirName) {
         return requireInternal(modulePath, dirName);
     };
 }
-return require_factory;
+module.exports = require_factory;
diff --git a/NativeScript/runtime/js/smart-stringify.js b/NativeScript/runtime/js/smart-stringify.js
index 5304d951..b7b06098 100644
--- a/NativeScript/runtime/js/smart-stringify.js
+++ b/NativeScript/runtime/js/smart-stringify.js
@@ -14,4 +14,4 @@ function smartStringify(object) {
     };
     return JSON.stringify(object, replacer, 2);
 }
-return smartStringify;
+module.exports = smartStringify;
diff --git a/eslint.config.mjs b/eslint.config.mjs
index d4d540dc..4b648a26 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -1,9 +1,9 @@
 // Lint setup for the runtime's builtin JavaScript (NativeScript/runtime/js).
-// Each file is compiled by BuiltinLoader as a FUNCTION BODY with the single
-// fixed parameter `binding` (see NativeScript/runtime/js/README.md), so
-// sourceType is "commonjs" (allows top-level return) and `binding` is a
-// declared global. no-undef is the typo net for binding-bag destructures and
-// native-global usage alike.
+// Each file is compiled by BuiltinLoader as a FUNCTION BODY with the fixed
+// parameters `exports`, `module` and `binding` (see
+// NativeScript/runtime/js/README.md), which are declared as globals here.
+// no-undef is the typo net for binding-bag destructures and native-global
+// usage alike.
 import globals from 'globals';
 
 export default [
@@ -11,9 +11,11 @@ export default [
     files: ['NativeScript/runtime/js/**/*.js'],
     languageOptions: {
       ecmaVersion: 2022,
-      sourceType: 'commonjs',
+      sourceType: 'script',
       globals: {
         ...globals.es2021,
+        exports: 'readonly',
+        module: 'readonly',
         binding: 'readonly',
         global: 'readonly',
         console: 'readonly',