From f7accdbced578b44d73dfc1d44020fa4d053c219 Mon Sep 17 00:00:00 2001
From: Joyee Cheung <joyeec9h3@gmail.com>
Date: Mon, 7 Oct 2024 17:26:10 +0200
Subject: [PATCH] process: add process.features.require_module

For detecting whether `require(esm)` is supported without triggering
the experimental warning.

PR-URL: https://github.com/nodejs/node/pull/55241
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
---
 doc/api/modules.md                            |  3 ++
 doc/api/process.md                            | 12 ++++++
 lib/internal/bootstrap/node.js                |  3 ++
 .../test-require-module-feature-detect.js     | 37 +++++++++++++++++++
 test/parallel/test-process-features.js        |  1 +
 5 files changed, 56 insertions(+)
 create mode 100644 test/es-module/test-require-module-feature-detect.js

diff --git a/doc/api/modules.md b/doc/api/modules.md
index 86f5df057e9a2f..9e4d3a223b8df6 100644
--- a/doc/api/modules.md
+++ b/doc/api/modules.md
@@ -318,6 +318,8 @@ experimental and can be disabled using `--no-experimental-require-module`.
 When `require()` actually encounters an ES module for the
 first time in the process, it will emit an experimental warning. The
 warning is expected to be removed when this feature stablizes.
+This feature can be detected by checking if
+[`process.features.require_module`][] is `true`.
 
 ## All together
 
@@ -1280,6 +1282,7 @@ This section was moved to
 [`node:test`]: test.md
 [`package.json`]: packages.md#nodejs-packagejson-field-definitions
 [`path.dirname()`]: path.md#pathdirnamepath
+[`process.features.require_module`]: process.md#processfeaturesrequire_module
 [`require.main`]: #requiremain
 [exports shortcut]: #exports-shortcut
 [module resolution]: #all-together
diff --git a/doc/api/process.md b/doc/api/process.md
index 0008ecbbc01b40..73d514f1f4a8d2 100644
--- a/doc/api/process.md
+++ b/doc/api/process.md
@@ -1936,6 +1936,17 @@ added: v0.5.3
 
 A boolean value that is `true` if the current Node.js build includes support for IPv6.
 
+## `process.features.require_module`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* {boolean}
+
+A boolean value that is `true` if the current Node.js build supports
+[loading ECMAScript modules using `require()`][].
+
 ## `process.features.tls`
 
 <!-- YAML
@@ -4431,6 +4442,7 @@ cases:
 [built-in modules with mandatory `node:` prefix]: modules.md#built-in-modules-with-mandatory-node-prefix
 [debugger]: debugger.md
 [deprecation code]: deprecations.md
+[loading ECMAScript modules using `require()`]: modules.md#loading-ecmascript-modules-using-require
 [note on process I/O]: #a-note-on-process-io
 [process.cpuUsage]: #processcpuusagepreviousvalue
 [process_emit_warning]: #processemitwarningwarning-type-code-ctor
diff --git a/lib/internal/bootstrap/node.js b/lib/internal/bootstrap/node.js
index ee83a555170c3b..e06854deaba5a0 100644
--- a/lib/internal/bootstrap/node.js
+++ b/lib/internal/bootstrap/node.js
@@ -279,6 +279,9 @@ const features = {
   get cached_builtins() {
     return binding.hasCachedBuiltins();
   },
+  get require_module() {
+    return getOptionValue('--experimental-require-module');
+  },
 };
 
 ObjectDefineProperty(process, 'features', {
diff --git a/test/es-module/test-require-module-feature-detect.js b/test/es-module/test-require-module-feature-detect.js
new file mode 100644
index 00000000000000..8af5bc77d7b32e
--- /dev/null
+++ b/test/es-module/test-require-module-feature-detect.js
@@ -0,0 +1,37 @@
+'use strict';
+
+// This tests that process.features.require_module can be used to feature-detect
+// require(esm) without triggering a warning.
+
+require('../common');
+const { spawnSyncAndAssert } = require('../common/child_process');
+
+spawnSyncAndAssert(process.execPath, [
+  '--experimental-require-module',
+  '-p',
+  'process.features.require_module',
+], {
+  trim: true,
+  stdout: 'true',
+  stderr: '',  // Should not emit warnings.
+});
+
+// It is now enabled by default.
+spawnSyncAndAssert(process.execPath, [
+  '-p',
+  'process.features.require_module',
+], {
+  trim: true,
+  stdout: 'true',
+  stderr: '',  // Should not emit warnings.
+});
+
+spawnSyncAndAssert(process.execPath, [
+  '--no-experimental-require-module',
+  '-p',
+  'process.features.require_module',
+], {
+  trim: true,
+  stdout: 'false',
+  stderr: '',  // Should not emit warnings.
+});
diff --git a/test/parallel/test-process-features.js b/test/parallel/test-process-features.js
index bd75db439aecc4..19b1c3a4f480e1 100644
--- a/test/parallel/test-process-features.js
+++ b/test/parallel/test-process-features.js
@@ -14,6 +14,7 @@ const expectedKeys = new Map([
   ['tls_ocsp', ['boolean']],
   ['tls', ['boolean']],
   ['cached_builtins', ['boolean']],
+  ['require_module', ['boolean']],
   ['typescript', ['boolean', 'string']],
 ]);