lib: expose global CloseEvent

This PR adds `CloseEvent` as a global, which can be disabled via the --no-experimental-websocket flag.

```js
const ws = new WebSocket('...')

ws.addEventListener('close', (event) => {
  assert(event instanceof CloseEvent)
})

```

Fixes: #50275

Author: KhafraDev

doc/api/globals.md

@@ -322,6 +322,19 @@ added: v0.0.1
 
 [`clearTimeout`][] is described in the [timers][] section.
 
+## `CloseEvent`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+<!-- type=global -->
+
+The `CloseEvent` class. See [`CloseEvent`][] for more details.
+
+A browser-compatible implementation of [`CloseEvent`][]. Disable this API
+with the [`--no-experimental-websocket`][] CLI flag.
+
 ## Class: `CompressionStream`
 
 <!-- YAML
@@ -1156,6 +1169,7 @@ A browser-compatible implementation of [`WritableStreamDefaultWriter`][].
 [`--no-experimental-websocket`]: cli.md#--no-experimental-websocket
 [`AbortController`]: https://developer.mozilla.org/en-US/docs/Web/API/AbortController
 [`ByteLengthQueuingStrategy`]: webstreams.md#class-bytelengthqueuingstrategy
+[`CloseEvent`]: https://developer.mozilla.org/en-US/docs/Web/API/CloseEvent/CloseEvent
 [`CompressionStream`]: webstreams.md#class-compressionstream
 [`CountQueuingStrategy`]: webstreams.md#class-countqueuingstrategy
 [`CustomEvent` Web API]: https://dom.spec.whatwg.org/#customevent

lib/eslint.config_partial.mjs

@@ -73,6 +73,10 @@ export default [
           name: 'ByteLengthQueuingStrategy',
           message: "Use `const { ByteLengthQueuingStrategy } = require('internal/webstreams/queuingstrategies')` instead of the global.",
         },
+        {
+          name: 'CloseEvent',
+          message: "Use `const { CloseEvent } = require('internal/deps/undici/undici');` instead of the global.",
+        },
         {
           name: 'CompressionStream',
           message: "Use `const { CompressionStream } = require('internal/webstreams/compression')` instead of the global.",

lib/internal/bootstrap/web/exposed-window-or-worker.js

@@ -84,7 +84,7 @@ ObjectDefineProperty(globalThis, 'fetch', {
 // https://fetch.spec.whatwg.org/#request-class
 // https://fetch.spec.whatwg.org/#response-class
 exposeLazyInterfaces(globalThis, 'internal/deps/undici/undici', [
-  'FormData', 'Headers', 'Request', 'Response', 'MessageEvent',
+  'FormData', 'Headers', 'Request', 'Response', 'MessageEvent', 'CloseEvent',
 ]);
 
 // https://html.spec.whatwg.org/multipage/server-sent-events.html#server-sent-events.org/

lib/internal/process/pre_execution.js

@@ -304,6 +304,7 @@ function setupWarningHandler() {
 function setupWebsocket() {
   if (getOptionValue('--no-experimental-websocket')) {
     delete globalThis.WebSocket;
+    delete globalThis.CloseEvent;
   }
 }
 

test/common/globals.js

@@ -127,6 +127,7 @@ const webIdlExposedWindow = new Set([
   'Response',
   'WebSocket',
   'EventSource',
+  'CloseEvent',
 ]);
 
 const nodeGlobals = new Set([

test/eslint.config_partial.mjs

@@ -13,6 +13,7 @@ export default [
     languageOptions: {
       globals: {
         ...globals.node,
+        CloseEvent: true,
       },
     },
     rules: {

test/parallel/test-websocket-disabled.js

@@ -5,3 +5,4 @@ require('../common');
 const assert = require('assert');
 
 assert.strictEqual(typeof WebSocket, 'undefined');
+assert.strictEqual(typeof CloseEvent, 'undefined');

test/parallel/test-websocket.js

@@ -4,3 +4,4 @@ require('../common');
 const assert = require('assert');
 
 assert.strictEqual(typeof WebSocket, 'function');
+assert.strictEqual(typeof CloseEvent, 'function');