refactor(shim): Move node CustomEvent polyfill to Platform.shim (#357)

src/platform/deno.ts

@@ -105,7 +105,8 @@ Platform.load({
   Headers: globalThis.Headers,
   FormData: globalThis.FormData,
   File: globalThis.File,
-  ReadableStream: globalThis.ReadableStream
+  ReadableStream: globalThis.ReadableStream,
+  CustomEvent: globalThis.CustomEvent
 });
 
 export * from './lib.js';

src/platform/node.ts

@@ -17,6 +17,7 @@ import os from 'os';
 import fs from 'fs/promises';
 import { readFileSync } from 'fs';
 import DOMParser from './polyfills/server-dom.js';
+import CustomEvent from './polyfills/node-custom-event.js';
 import { fileURLToPath } from 'url';
 import evaluate from './jsruntime/jinter.js';
 
@@ -123,7 +124,8 @@ Platform.load({
   Headers: Headers as unknown as typeof globalThis.Headers,
   FormData: FormData as unknown as typeof globalThis.FormData,
   File: File as unknown as typeof globalThis.File,
-  ReadableStream: ReadableStream as unknown as typeof globalThis.ReadableStream
+  ReadableStream: ReadableStream as unknown as typeof globalThis.ReadableStream,
+  CustomEvent: CustomEvent as unknown as typeof globalThis.CustomEvent
 });
 
 export * from './lib.js';

src/platform/polyfills/node-custom-event.ts

@@ -0,0 +1,13 @@
+// See https://github.com/nodejs/node/issues/40678#issuecomment-1126944677
+export default class CustomEvent extends Event {
+  #detail;
+
+  constructor(type: string, options?: CustomEventInit<any[]>) {
+    super(type, options);
+    this.#detail = options?.detail ?? null;
+  }
+
+  get detail() {
+    return this.#detail;
+  }
+}

src/platform/web.ts

@@ -115,7 +115,8 @@ Platform.load({
   Headers: globalThis.Headers,
   FormData: globalThis.FormData,
   File: globalThis.File,
-  ReadableStream: globalThis.ReadableStream
+  ReadableStream: globalThis.ReadableStream,
+  CustomEvent: globalThis.CustomEvent
 });
 
 export * from './lib.js';

src/types/PlatformShim.ts

@@ -27,6 +27,7 @@ interface PlatformShim {
     FormData: typeof FormData;
     File: typeof File;
     ReadableStream: typeof ReadableStream;
+    CustomEvent: typeof CustomEvent;
 }
 
 export default PlatformShim;

src/utils/EventEmitterLike.ts

@@ -1,22 +1,4 @@
-// Polyfill CustomEvents on node
-if (!Reflect.has(globalThis, 'CustomEvent')) {
-
-  // See https://github.com/nodejs/node/issues/40678#issuecomment-1126944677
-  class CustomEvent extends Event {
-    #detail;
-
-    constructor(type: string, options?: CustomEventInit<any[]>) {
-      super(type, options);
-      this.#detail = options?.detail ?? null;
-    }
-
-    get detail() {
-      return this.#detail;
-    }
-  }
-
-  Reflect.set(globalThis, 'CustomEvent', CustomEvent);
-}
+import { Platform } from './Utils.js';
 
 export default class EventEmitterLike extends EventTarget {
   #legacy_listeners = new Map<(...args: any[]) => void, EventListener>();
@@ -26,13 +8,13 @@ export default class EventEmitterLike extends EventTarget {
   }
 
   emit(type: string, ...args: any[]) {
-    const event = new CustomEvent(type, { detail: args });
+    const event = new Platform.shim.CustomEvent(type, { detail: args });
     this.dispatchEvent(event);
   }
 
   on(type: string, listener: (...args: any[]) => void) {
     const wrapper: EventListener = (ev) => {
-      if (ev instanceof CustomEvent) {
+      if (ev instanceof Platform.shim.CustomEvent) {
         listener(...ev.detail);
       } else {
         listener(ev);
@@ -44,7 +26,7 @@ export default class EventEmitterLike extends EventTarget {
 
   once(type: string, listener: (...args: any[]) => void) {
     const wrapper: EventListener = (ev) => {
-      if (ev instanceof CustomEvent) {
+      if (ev instanceof Platform.shim.CustomEvent) {
         listener(...ev.detail);
       } else {
         listener(ev);