[v18.x backport] lib: enable global CustomEvent by default

doc/api/cli.md

@@ -353,14 +353,6 @@ when `Error.stack` is accessed. If you access `Error.stack` frequently
 in your application, take into account the performance implications
 of `--enable-source-maps`.
 
-### `--experimental-global-customevent`
-
-<!-- YAML
-added: v18.7.0
--->
-
-Expose the [CustomEvent Web API][] on the global scope.
-
 ### `--experimental-global-webcrypto`
 
 <!-- YAML
@@ -462,6 +454,14 @@ added: v18.0.0
 
 Disable experimental support for the [Fetch API][].
 
+### `--no-experimental-global-customevent`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+Disable exposition of [CustomEvent Web API][] on the global scope.
+
 ### `--no-experimental-repl-await`
 
 <!-- YAML
@@ -1966,7 +1966,6 @@ Node.js options that are allowed are:
 * `--enable-source-maps`
 * `--experimental-abortcontroller`
 * `--experimental-default-type`
-* `--experimental-global-customevent`
 * `--experimental-global-webcrypto`
 * `--experimental-import-meta-resolve`
 * `--experimental-json-modules`
@@ -2000,6 +1999,7 @@ Node.js options that are allowed are:
 * `--no-addons`
 * `--no-deprecation`
 * `--no-experimental-fetch`
+* `--no-experimental-global-customevent`
 * `--no-experimental-repl-await`
 * `--no-extra-info-on-fatal-exception`
 * `--no-force-async-hooks-checks`

doc/api/globals.md

@@ -390,10 +390,14 @@ only if the Node.js binary was compiled with including support for the
 
 <!-- YAML
 added: v18.7.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/52270
+    description: No longer behind `--experimental-global-customevent` CLI flag.
 -->
 
-> Stability: 1 - Experimental. Enable this API with the
-> [`--experimental-global-customevent`][] CLI flag.
+> Stability: 1 - Experimental. Disable this API with the
+> [`--no-experimental-global-customevent`][] CLI flag.
 
 <!-- type=global -->
 
@@ -885,9 +889,9 @@ A browser-compatible implementation of [`WritableStreamDefaultWriter`][].
 [CommonJS module]: modules.md
 [ECMAScript module]: esm.md
 [Web Crypto API]: webcrypto.md
-[`--experimental-global-customevent`]: cli.md#--experimental-global-customevent
 [`--experimental-global-webcrypto`]: cli.md#--experimental-global-webcrypto
 [`--no-experimental-fetch`]: cli.md#--no-experimental-fetch
+[`--no-experimental-global-customevent`]: cli.md#--no-experimental-global-customevent
 [`AbortController`]: https://developer.mozilla.org/en-US/docs/Web/API/AbortController
 [`ByteLengthQueuingStrategy`]: webstreams.md#class-bytelengthqueuingstrategy
 [`CompressionStream`]: webstreams.md#class-compressionstream

doc/node.1

@@ -145,9 +145,6 @@ Interpret as either ES modules or CommonJS modules input via --eval or STDIN, wh
 .js or extensionless files with no sibling or parent package.json;
 .js or extensionless files whose nearest parent package.json lacks a "type" field, unless under node_modules.
 .
-.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.
 .
@@ -174,6 +171,9 @@ Enable code coverage in the test runner.
 .It Fl -no-experimental-fetch
 Disable experimental support for the Fetch API.
 .
+.It Fl -no-experimental-global-customevent
+Disable exposition of the CustomEvent on the global scope.
+.
 .It Fl -no-experimental-repl-await
 Disable top-level await keyword support in REPL.
 .

lib/internal/process/pre_execution.js

@@ -345,7 +345,7 @@ function setupCodeCoverage() {
 //                removed.
 function setupCustomEvent() {
   if (process.config.variables.node_no_browser_globals ||
-      !getOptionValue('--experimental-global-customevent')) {
+      getOptionValue('--no-experimental-global-customevent')) {
     return;
   }
   const { CustomEvent } = require('internal/event_target');

src/node_options.cc

@@ -385,7 +385,8 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
   AddOption("--experimental-global-customevent",
             "expose experimental CustomEvent on the global scope",
             &EnvironmentOptions::experimental_global_customevent,
-            kAllowedInEnvvar);
+            kAllowedInEnvironment,
+            true);
   AddOption("--experimental-global-webcrypto",
             "expose experimental Web Crypto API on the global scope",
             &EnvironmentOptions::experimental_global_web_crypto,

src/node_options.h

@@ -111,7 +111,7 @@ class EnvironmentOptions : public Options {
   std::string dns_result_order;
   bool enable_source_maps = false;
   bool experimental_fetch = true;
-  bool experimental_global_customevent = false;
+  bool experimental_global_customevent = true;
   bool experimental_global_web_crypto = false;
   bool experimental_https_modules = false;
   std::string experimental_specifier_resolution;

test/parallel/test-global-customevent-disabled.js

@@ -0,0 +1,7 @@
+// Flags: --no-experimental-global-customevent
+'use strict';
+
+require('../common');
+const { strictEqual } = require('node:assert');
+
+strictEqual(typeof CustomEvent, 'undefined');

test/parallel/test-global-customevent.js

@@ -1,4 +1,4 @@
-// Flags: --experimental-global-customevent --expose-internals
+// Flags: --expose-internals
 'use strict';
 
 require('../common');

test/parallel/test-repl-tab-complete.js

@@ -405,7 +405,7 @@ putIn.run([
   'var custom = "test";',
 ]);
 testMe.complete('cus', common.mustCall(function(error, data) {
-  assert.deepStrictEqual(data, [['custom'], 'cus']);
+  assert.deepStrictEqual(data, [['CustomEvent', 'custom'], 'cus']);
 }));
 
 // Make sure tab completion doesn't crash REPL with half-baked proxy objects.

test/wpt/test-events.js

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