Use process.builtinModule() when available

src/lib/libatomic.js

@@ -172,7 +172,7 @@ addToLibrary({
 
   emscripten_num_logical_cores: () =>
 #if ENVIRONMENT_MAY_BE_NODE
-    ENVIRONMENT_IS_NODE ? require('node:os').cpus().length :
+    ENVIRONMENT_IS_NODE ? getBuiltinModule('os').cpus().length :
 #endif
     navigator['hardwareConcurrency'],
 

src/lib/libcore.js

@@ -377,7 +377,7 @@ addToLibrary({
       var cmdstr = UTF8ToString(command);
       if (!cmdstr.length) return 0; // this is what glibc seems to do (shell works test?)
 
-      var cp = require('node:child_process');
+      var cp = getBuiltinModule('child_process');
       var ret = cp.spawnSync(cmdstr, [], {shell:true, stdio:'inherit'});
 
       var _W_EXITCODE = (ret, sig) => ((ret) << 8 | (sig));

src/lib/libembind_gen.js

@@ -924,7 +924,7 @@ var LibraryEmbind = {
     const printer = new TsPrinter(moduleDefinitions);
 #endif
     const output = printer.print();
-    var fs = require('node:fs');
+    var fs = getBuiltinModule('fs');
     fs.writeFileSync(process.argv[2], output + '\n');
   },
 

src/lib/libnodepath.js

@@ -12,7 +12,7 @@
 // operations. Hence, using `nodePath` should be safe here.
 
 addToLibrary({
-  $nodePath: "require('node:path')",
+  $nodePath: "getBuiltinModule('path')",
   $PATH__deps: ['$nodePath'],
   $PATH: `{
     isAbs: nodePath.isAbsolute,

src/lib/libnoderawfs.js

@@ -10,7 +10,7 @@ addToLibrary({
     if (!ENVIRONMENT_IS_NODE) {
       throw new Error("NODERAWFS is currently only supported on Node.js environment.")
     }
-    var nodeTTY = require('node:tty');
+    var nodeTTY = getBuiltinModule('tty');
     function _wrapNodeError(func) {
       return (...args) => {
         try {

src/lib/libsockfs.js

@@ -5,10 +5,25 @@
  */
 
 addToLibrary({
+#if ENVIRONMENT_MAY_BE_NODE && EXPORT_ES6
+  // ESM has no native `require`. Lazily construct one (node-gated, so it never
+  // runs during web startup) for loading the non-builtin `ws` module. The call
+  // site stays a literal `require('ws')` so third-party bundlers can still
+  // statically discover the dependency.
+  $require: undefined,
+  $ensureCreateRequire__deps: ['$require'],
+  $ensureCreateRequire: () => {
+    require ??= getBuiltinModule('module').createRequire(import.meta.url);
+  },
+#endif
   $SOCKFS__postset: () => {
     addAtInit('SOCKFS.root = FS.mount(SOCKFS, {}, null);');
   },
+#if ENVIRONMENT_MAY_BE_NODE && EXPORT_ES6
+  $SOCKFS__deps: ['$FS', '$ensureCreateRequire'],
+#else
   $SOCKFS__deps: ['$FS'],
+#endif
   $SOCKFS: {
 #if expectToReceiveOnModule('websocket')
     websocketArgs: {},
@@ -216,6 +231,9 @@ addToLibrary({
             var WebSocketConstructor;
 #if ENVIRONMENT_MAY_BE_NODE
             if (ENVIRONMENT_IS_NODE) {
+#if EXPORT_ES6
+              ensureCreateRequire();
+#endif
               WebSocketConstructor = /** @type{(typeof WebSocket)} */(require('ws'));
             } else
 #endif // ENVIRONMENT_MAY_BE_NODE
@@ -518,6 +536,9 @@ addToLibrary({
         if (sock.server) {
            throw new FS.ErrnoError({{{ cDefs.EINVAL }}});  // already listening
         }
+#if EXPORT_ES6
+        ensureCreateRequire();
+#endif
         var WebSocketServer = require('ws').Server;
         var host = sock.saddr;
 #if SOCKET_DEBUG

src/lib/libwasi.js

@@ -570,7 +570,7 @@ var WasiLibrary = {
 #if ENVIRONMENT_MAY_BE_NODE && MIN_NODE_VERSION < 190000
     // This block is not needed on v19+ since crypto.getRandomValues is builtin
     if (ENVIRONMENT_IS_NODE) {
-      var nodeCrypto = require('node:crypto');
+      var nodeCrypto = getBuiltinModule('crypto');
       return (view) => (nodeCrypto.randomFillSync(view), 0);
     }
 #endif // ENVIRONMENT_MAY_BE_NODE

src/lib/libwasm_worker.js

@@ -295,7 +295,7 @@ if (ENVIRONMENT_IS_WASM_WORKER
 
   emscripten_navigator_hardware_concurrency: () => {
 #if ENVIRONMENT_MAY_BE_NODE
-    if (ENVIRONMENT_IS_NODE) return require('node:os').cpus().length;
+    if (ENVIRONMENT_IS_NODE) return getBuiltinModule('os').cpus().length;
 #endif
     return navigator['hardwareConcurrency'];
   },

src/preamble.js

@@ -553,7 +553,7 @@ function instantiateSync(file, info) {
   var binary = getBinarySync(file);
 #if NODE_CODE_CACHING
   if (ENVIRONMENT_IS_NODE) {
-    var v8 = require('node:v8');
+    var v8 = getBuiltinModule('v8');
     // Include the V8 version in the cache name, so that we don't try to
     // load cached code from another version, which fails silently (it seems
     // to load ok, but we do actually recompile the binary every time).

src/runtime_debug.js

@@ -15,8 +15,8 @@ function dbg(...args) {
   // See https://github.com/emscripten-core/emscripten/issues/14804
   if (ENVIRONMENT_IS_NODE) {
     // TODO(sbc): Unify with err/out implementation in shell.sh.
-    var fs = require('node:fs');
-    var utils = require('node:util');
+    var fs = getBuiltinModule('fs');
+    var utils = getBuiltinModule('util');
     function stringify(a) {
       switch (typeof a) {
         case 'object': return utils.inspect(a);

src/shell.js

@@ -104,18 +104,26 @@ if (ENVIRONMENT_IS_PTHREAD) {
 #endif
 #endif
 
-#if ENVIRONMENT_MAY_BE_NODE && (EXPORT_ES6 || PTHREADS || WASM_WORKERS)
+#if ENVIRONMENT_MAY_BE_NODE
+// `process.getBuiltinModule()` loads builtins under both CJS and ESM. On older
+// node (pre v18.20.4/v20.16/v22.3) fall back to `require()`.
+var getBuiltinModule;
 if (ENVIRONMENT_IS_NODE) {
+  if (process['getBuiltinModule']) {
+    getBuiltinModule = process['getBuiltinModule'];
+  } else {
 #if EXPORT_ES6
-  // When building an ES module `require` is not normally available.
-  // We need to use `createRequire()` to construct the require()` function.
-  const { createRequire } = await import('node:module');
-  /** @suppress{duplicate} */
-  var require = createRequire(import.meta.url);
+    getBuiltinModule = (await import('node:module')).createRequire(import.meta.url);
+#else
+    getBuiltinModule = require;
 #endif
+  }
+}
+#endif // ENVIRONMENT_MAY_BE_NODE
 
-#if PTHREADS || WASM_WORKERS
-  var worker_threads = require('node:worker_threads');
+#if ENVIRONMENT_MAY_BE_NODE && (PTHREADS || WASM_WORKERS)
+if (ENVIRONMENT_IS_NODE) {
+  var worker_threads = getBuiltinModule('worker_threads');
   globalThis.Worker = worker_threads.Worker;
   ENVIRONMENT_IS_WORKER = !worker_threads.isMainThread;
 #if PTHREADS
@@ -126,9 +134,8 @@ if (ENVIRONMENT_IS_NODE) {
 #if WASM_WORKERS
   ENVIRONMENT_IS_WASM_WORKER = ENVIRONMENT_IS_WORKER && worker_threads.workerData == 'em-ww'
 #endif
-#endif // PTHREADS || WASM_WORKERS
 }
-#endif // ENVIRONMENT_MAY_BE_NODE && (EXPORT_ES6 || PTHREADS || WASM_WORKERS)
+#endif // ENVIRONMENT_MAY_BE_NODE && (PTHREADS || WASM_WORKERS)
 
 // --pre-jses are emitted after the Module integration code, so that they can
 // refer to Module (if they choose; they can also define Module)
@@ -197,11 +204,11 @@ if (ENVIRONMENT_IS_NODE) {
 
   // These modules will usually be used on Node.js. Load them eagerly to avoid
   // the complexity of lazy-loading.
-  var fs = require('node:fs');
+  var fs = getBuiltinModule('fs');
 
 #if EXPORT_ES6
   if (_scriptName.startsWith('file:')) {
-    scriptDirectory = require('node:path').dirname(require('node:url').fileURLToPath(_scriptName)) + '/';
+    scriptDirectory = getBuiltinModule('path').dirname(getBuiltinModule('url').fileURLToPath(_scriptName)) + '/';
   }
 #else
   scriptDirectory = __dirname + '/';
@@ -346,7 +353,7 @@ if (!ENVIRONMENT_IS_AUDIO_WORKLET)
 var defaultPrint = console.log.bind(console);
 var defaultPrintErr = console.error.bind(console);
 if (ENVIRONMENT_IS_NODE) {
-  var utils = require('node:util');
+  var utils = getBuiltinModule('util');
   var stringify = (a) => typeof a == 'object' ? utils.inspect(a) : a;
   defaultPrint = (...args) => fs.writeSync(1, args.map(stringify).join(' ') + '\n');
   defaultPrintErr = (...args) => fs.writeSync(2, args.map(stringify).join(' ') + '\n');

src/shell_minimal.js

@@ -33,6 +33,21 @@ var Module = {{{ EXPORT_NAME }}};
 
 #if ENVIRONMENT_MAY_BE_NODE
 var ENVIRONMENT_IS_NODE = {{{ nodeDetectionCode() }}};
+
+// `process.getBuiltinModule()` loads builtins under both CJS and ESM. On older
+// node (pre v18.20.4/v20.16/v22.3) fall back to `require()`.
+var getBuiltinModule;
+if (ENVIRONMENT_IS_NODE) {
+  if (process['getBuiltinModule']) {
+    getBuiltinModule = process['getBuiltinModule'];
+  } else {
+#if EXPORT_ES6
+    getBuiltinModule = (await import('node:module')).createRequire(import.meta.url);
+#else
+    getBuiltinModule = require;
+#endif
+  }
+}
 #endif
 
 #if ENVIRONMENT_MAY_BE_SHELL
@@ -59,7 +74,7 @@ var ENVIRONMENT_IS_WORKER = !!globalThis.WorkerGlobalScope;
 
 #if ENVIRONMENT_MAY_BE_NODE && (PTHREADS || WASM_WORKERS)
 if (ENVIRONMENT_IS_NODE) {
-  var worker_threads = require('node:worker_threads');
+  var worker_threads = getBuiltinModule('worker_threads');
   globalThis.Worker = worker_threads.Worker;
   ENVIRONMENT_IS_WORKER = !worker_threads.isMainThread;
 }
@@ -104,7 +119,7 @@ if (ENVIRONMENT_IS_NODE && ENVIRONMENT_IS_SHELL) {
 var defaultPrint = console.log.bind(console);
 var defaultPrintErr = console.error.bind(console);
 if (ENVIRONMENT_IS_NODE) {
-  var fs = require('node:fs');
+  var fs = getBuiltinModule('fs');
   defaultPrint = (...args) => fs.writeSync(1, args.join(' ') + '\n');
   defaultPrintErr = (...args) => fs.writeSync(2, args.join(' ') + '\n');
 }
@@ -179,7 +194,7 @@ if (!ENVIRONMENT_IS_PTHREAD) {
 // Wasm or Wasm2JS loading:
 
 if (ENVIRONMENT_IS_NODE) {
-  var fs = require('node:fs');
+  var fs = getBuiltinModule('fs');
 #if WASM == 2
   if (globalThis.WebAssembly) Module['wasm'] = fs.readFileSync(__dirname + '/{{{ TARGET_BASENAME }}}.wasm');
   else eval(fs.readFileSync(__dirname + '/{{{ TARGET_BASENAME }}}.wasm.js')+'');

test/codesize/test_codesize_hello_dylink_all.json

@@ -1,7 +1,7 @@
 {
-  "a.out.js": 268278,
+  "a.out.js": 268326,
   "a.out.nodebug.wasm": 587640,
-  "total": 855918,
+  "total": 855966,
   "sent": [
     "IMG_Init",
     "IMG_Load",

test/codesize/test_unoptimized_code_size.json

@@ -1,16 +1,16 @@
 {
-  "hello_world.js": 55076,
-  "hello_world.js.gz": 17352,
+  "hello_world.js": 55410,
+  "hello_world.js.gz": 17457,
   "hello_world.wasm": 15115,
   "hello_world.wasm.gz": 7464,
-  "no_asserts.js": 25903,
-  "no_asserts.js.gz": 8768,
+  "no_asserts.js": 26237,
+  "no_asserts.js.gz": 8876,
   "no_asserts.wasm": 12229,
   "no_asserts.wasm.gz": 6004,
-  "strict.js": 52833,
-  "strict.js.gz": 16583,
+  "strict.js": 53167,
+  "strict.js.gz": 16688,
   "strict.wasm": 15115,
   "strict.wasm.gz": 7461,
-  "total": 176271,
-  "total_gz": 63632
+  "total": 177273,
+  "total_gz": 63950
 }

test/fs/test_nodefs_home.c

@@ -11,7 +11,7 @@
 int main(void)
 {
     EM_ASM(
-        var path = require("path");
+        var path = process.getBuiltinModule("path");
         var home = process.env.HOME;
         // On Windows HOME environment variable doesn't exist, but concatenating HOMEDRIVE and HOMEPATH
         // does the same thing.

test/fs/test_nodefs_rw.c

@@ -18,7 +18,7 @@ int main() {
 
   // write something locally with node
   EM_ASM(
-    var fs = require('fs');
+    var fs = process.getBuiltinModule('fs');
     fs.writeFileSync('foobar.txt', 'yeehaw');
   );
 
@@ -42,7 +42,7 @@ int main() {
 
   // validate the changes were persisted to the underlying fs
   EM_ASM(
-    var fs = require('fs');
+    var fs = process.getBuiltinModule('fs');
     var contents = fs.readFileSync('foobar.txt', { encoding: 'utf8' });
     assert(contents === 'cheez');
   );

test/test_other.py

@@ -1665,16 +1665,14 @@ def test_minimal_runtime_export_all_modularize(self):
 
     self.emcc('main.c', ['-sMODULARIZE=1', '-sMINIMAL_RUNTIME=2', '-sEXPORT_ALL', '-sEXPORT_ES6', '-o', 'test.mjs'])
 
-    # We must expose __dirname and require globally because emscripten
-    # uses those under the hood.
+    # We must expose __dirname globally because emscripten uses it under the
+    # hood (builtin modules are loaded via process.getBuiltinModule).
     create_file('main.mjs', '''
       import { dirname } from 'node:path';
-      import { createRequire } from 'node:module';
       import { fileURLToPath } from 'node:url';
 
       // `fileURLToPath` is used to get a valid path on Windows.
       globalThis.__dirname = dirname(fileURLToPath(import.meta.url));
-      globalThis.require = createRequire(import.meta.url);
 
       import Test from './test.mjs';
       async function main() {

tools/file_packager.py

@@ -627,11 +627,16 @@ def generate_preload_js(data_target, data_files, metadata):
   if options.support_node:
     ret += "    var isNode = globalThis.process && globalThis.process.versions && globalThis.process.versions.node && globalThis.process.type != 'renderer';\n"
 
-  if options.support_node and options.export_es6:
+  if options.support_node:
     ret += '''if (isNode) {
-    const { createRequire } = await import('node:module');
-    /** @suppress{duplicate} */
-    var require = createRequire(import.meta.url);
+    if (process['getBuiltinModule']) {
+      var getBuiltinModule = process['getBuiltinModule'];
+    } else {\n'''
+    if options.export_es6:
+      ret += '''      var getBuiltinModule = (await import('node:module')).createRequire(import.meta.url);\n'''
+    else:
+      ret += '''      var getBuiltinModule = require;\n'''
+    ret += '''    }
   }\n'''
 
   if options.export_es6:
@@ -910,7 +915,7 @@ def generate_preload_js(data_target, data_files, metadata):
     if options.support_node:
       node_support_code = '''
         if (isNode) {
-          var contents = require('fs').readFileSync(packageName);
+          var contents = getBuiltinModule('fs').readFileSync(packageName);
           return new Uint8Array(contents).buffer;
         }'''.strip()
 
@@ -1045,7 +1050,7 @@ def generate_preload_js(data_target, data_files, metadata):
     if options.support_node:
       node_support_code = '''
         if (isNode) {
-          var contents = require('fs').readFileSync(metadataUrl, 'utf8');
+          var contents = getBuiltinModule('fs').readFileSync(metadataUrl, 'utf8');
           // The await here is needed, even though JSON.parse is a sync API.  It works
           // around a issue with `removeRunDependency` otherwise being called to early
           // on the metadata object.