events: expose CustomEvent on global with CLI flag

Signed-off-by: Daeyeon Jeong daeyeon.dev@gmail.com

PR-URL: #43885
Backport-PR-URL: #44082
Fixes: #40678
Refs: #43514
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>

.eslintrc.js

@@ -320,6 +320,7 @@ module.exports = {
     'node-core/no-duplicate-requires': 'error',
   },
   globals: {
+    CustomEvent: 'readable',
     Crypto: 'readable',
     CryptoKey: 'readable',
     fetch: 'readable',

doc/api/cli.md

@@ -280,6 +280,14 @@ added: v16.15.0
 
 Enable experimental support for the [Fetch API][].
 
+### `--experimental-global-customevent`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Expose the [CustomEvent Web API][] on the global scope.
+
 ### `--experimental-global-webcrypto`
 
 <!-- YAML
@@ -1619,6 +1627,7 @@ Node.js options that are allowed are:
 * `--enable-source-maps`
 * `--experimental-abortcontroller`
 * `--experimental-fetch`
+* `--experimental-global-customevent`
 * `--experimental-global-webcrypto`
 * `--experimental-import-meta-resolve`
 * `--experimental-json-modules`
@@ -2041,6 +2050,7 @@ done
 [#42511]: https://github.com/nodejs/node/issues/42511
 [Chrome DevTools Protocol]: https://chromedevtools.github.io/devtools-protocol/
 [CommonJS]: modules.md
+[CustomEvent Web API]: https://dom.spec.whatwg.org/#customevent
 [ECMAScript module loader]: esm.md#loaders
 [Fetch API]: https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API
 [Modules loaders]: packages.md#modules-loaders

doc/api/globals.md

@@ -306,6 +306,19 @@ A browser-compatible implementation of {CryptoKey}. This global is available
 only if the Node.js binary was compiled with including support for the
 `node:crypto` module.
 
+## `CustomEvent`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental. Enable this API with the
+> [`--experimental-global-customevent`][] CLI flag.
+
+<!-- type=global -->
+
+A browser-compatible implementation of the [`CustomEvent` Web API][].
+
 ## `Event`
 
 <!-- YAML
@@ -607,8 +620,10 @@ The object that acts as the namespace for all W3C
 
 [Web Crypto API]: webcrypto.md
 [`--experimental-fetch`]: cli.md#--experimental-fetch
+[`--experimental-global-customevent`]: cli.md#--experimental-global-customevent
 [`--experimental-global-webcrypto`]: cli.md#--experimental-global-webcrypto
 [`AbortController`]: https://developer.mozilla.org/en-US/docs/Web/API/AbortController
+[`CustomEvent` Web API]: https://dom.spec.whatwg.org/#customevent
 [`EventTarget` and `Event` API]: events.md#eventtarget-and-event-api
 [`MessageChannel`]: worker_threads.md#class-messagechannel
 [`MessageEvent`]: https://developer.mozilla.org/en-US/docs/Web/API/MessageEvent/MessageEvent

doc/node.1

@@ -142,6 +142,9 @@ Enable Source Map V3 support for stack traces.
 .It Fl -experimental-fetch
 Enable experimental support for the Fetch API.
 .
+.It Fl -experimental-global-customevent
+Expose the CustomEvent on the global scope.
+.
 .It Fl -experimental-global-webcrypto
 Expose the Web Crypto API on the global scope.
 .

lib/.eslintrc.yaml

@@ -41,6 +41,8 @@ rules:
       message: Use `const { BroadcastChannel } = require('internal/worker/io');` instead of the global.
     - name: Buffer
       message: Use `const { Buffer } = require('buffer');` instead of the global.
+    - name: CustomEvent
+      message: Use `const { CustomEvent } = require('internal/event_target');` instead of the global.
     - name: Event
       message: Use `const { Event } = require('internal/event_target');` instead of the global.
     - name: EventTarget

lib/internal/bootstrap/pre_execution.js

@@ -42,6 +42,7 @@ function prepareMainThreadExecution(expandArgv1 = false,
   setupWarningHandler();
   setupFetch();
   setupWebCrypto();
+  setupCustomEvent();
 
   // Resolve the coverage directory to an absolute path, and
   // overwrite process.env so that the original path gets passed
@@ -232,6 +233,17 @@ function setupWebCrypto() {
   }
 }
 
+// TODO(daeyeon): move this to internal/bootstrap/browser when the CLI flag is
+//                removed.
+function setupCustomEvent() {
+  if (process.config.variables.node_no_browser_globals ||
+      !getOptionValue('--experimental-global-customevent')) {
+    return;
+  }
+  const { CustomEvent } = require('internal/event_target');
+  exposeInterface(globalThis, 'CustomEvent', CustomEvent);
+}
+
 // Setup User-facing NODE_V8_COVERAGE environment variable that writes
 // ScriptCoverage to a specified file.
 function setupCoverageHooks(dir) {
@@ -579,6 +591,7 @@ module.exports = {
   setupWarningHandler,
   setupFetch,
   setupWebCrypto,
+  setupCustomEvent,
   setupDebugEnv,
   setupPerfHooks,
   prepareMainThreadExecution,

lib/internal/main/worker_thread.js

@@ -19,6 +19,7 @@ const {
   setupWarningHandler,
   setupFetch,
   setupWebCrypto,
+  setupCustomEvent,
   setupDebugEnv,
   setupPerfHooks,
   initializeDeprecations,
@@ -71,6 +72,7 @@ setupDebugEnv();
 setupWarningHandler();
 setupFetch();
 setupWebCrypto();
+setupCustomEvent();
 initializeSourceMapsHandlers();
 
 // Since worker threads cannot switch cwd, we do not need to

src/node_options.cc

@@ -339,6 +339,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             &EnvironmentOptions::experimental_fetch,
             kAllowedInEnvironment);
   AddOption("--experimental-json-modules", "", NoOp{}, kAllowedInEnvironment);
+  AddOption("--experimental-global-customevent",
+            "expose experimental CustomEvent on the global scope",
+            &EnvironmentOptions::experimental_global_customevent,
+            kAllowedInEnvironment);
   AddOption("--experimental-global-webcrypto",
             "expose experimental Web Crypto API on the global scope",
             &EnvironmentOptions::experimental_global_web_crypto,

src/node_options.h

@@ -109,6 +109,7 @@ class EnvironmentOptions : public Options {
   bool enable_source_maps = false;
   bool experimental_https_modules = false;
   bool experimental_fetch = false;
+  bool experimental_global_customevent = false;
   bool experimental_global_web_crypto = false;
   std::string experimental_specifier_resolution;
   bool experimental_wasm_modules = false;

test/common/index.js

@@ -315,6 +315,9 @@ if (hasCrypto && global.crypto) {
   knownGlobals.push(global.CryptoKey);
   knownGlobals.push(global.SubtleCrypto);
 }
+if (global.CustomEvent) {
+  knownGlobals.push(global.CustomEvent);
+}
 
 function allowGlobals(...allowlist) {
   knownGlobals = knownGlobals.concat(allowlist);

test/parallel/test-global-customevent.js

@@ -0,0 +1,11 @@
+// Flags: --experimental-global-customevent --expose-internals
+'use strict';
+
+require('../common');
+const { strictEqual, ok } = require('node:assert');
+const { CustomEvent: internalCustomEvent } = require('internal/event_target');
+
+// Global
+ok(CustomEvent);
+
+strictEqual(CustomEvent, internalCustomEvent);

test/wpt/status/dom/events.json

@@ -20,17 +20,13 @@
     "fail": {
       "unexpected": [
         "assert_true: expected true got false",
-        "assert_array_equals: lengths differ, expected array [\"bubbles\", \"cancelable\"] length 2, got [\"cancelable\", \"bubbles\", \"sweet\"] length 3",
-        "CustomEvent is not defined"
+        "assert_array_equals: lengths differ, expected array [\"bubbles\", \"cancelable\"] length 2, got [\"cancelable\", \"bubbles\", \"sweet\"] length 3"
       ]
     }
   },
   "EventListener-addEventListener.sub.window.js": {
     "fail": "document is not defined"
   },
-  "EventTarget-constructible.any.js": {
-    "fail": "CustomEvent is not defined"
-  },
   "relatedTarget.window.js": {
     "fail": "document is not defined"
   },

test/wpt/test-events.js

@@ -4,4 +4,6 @@ const { WPTRunner } = require('../common/wpt');
 
 const runner = new WPTRunner('dom/events');
 
+runner.setFlags(['--experimental-global-customevent']);
+
 runner.runJsTests();