nodejs · GeoffreyBooth · Sep 30, 2023 · Oct 2, 2023 · Oct 3, 2023 · Oct 3, 2023
diff --git a/doc/api/esm.md b/doc/api/esm.md
@@ -1009,8  1009,12 @@ _isImports_, _conditions_)
 > 5. Let _packageURL_ be the result of **LOOKUP\_PACKAGE\_SCOPE**(_url_).
 > 6. Let _pjson_ be the result of **READ\_PACKAGE\_JSON**(_packageURL_).
 > 7. If _pjson?.type_ exists and is _"module"_, then
->    1. If _url_ ends in _".js"_, then
->       1. Return _"module"_.
 >    1. If _url_ ends in _".js"_ or has no file extension, then
 >       1. If `--experimental-wasm-modules` is enabled and the file at _url_
 >          contains the header for a WebAssembly module, then
 >          1. Return _"wasm"_.
 >       2. Otherwise,
 >          1. Return _"module"_.
 >    2. Return **undefined**.
 > 8. Otherwise,
 >    1. Return **undefined**.

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
@@ -1760,13  1760,7 @@ E('ERR_UNHANDLED_ERROR',
 E('ERR_UNKNOWN_BUILTIN_MODULE', 'No such built-in module: %s', Error);
 E('ERR_UNKNOWN_CREDENTIAL', '%s identifier does not exist: %s', Error);
 E('ERR_UNKNOWN_ENCODING', 'Unknown encoding: %s', TypeError);
-E('ERR_UNKNOWN_FILE_EXTENSION', (ext, path, suggestion) => {
-  let msg = `Unknown file extension "${ext}" for ${path}`;
-  if (suggestion) {
-    msg  = `. ${suggestion}`;
-  }
-  return msg;
-}, TypeError);
 E('ERR_UNKNOWN_FILE_EXTENSION', 'Unknown file extension "%s" for %s', TypeError);
 E('ERR_UNKNOWN_MODULE_FORMAT', 'Unknown module format: %s for URL %s',
   RangeError);
 E('ERR_UNKNOWN_SIGNAL', 'Unknown signal: %s', TypeError);

diff --git a/lib/internal/modules/esm/get_format.js b/lib/internal/modules/esm/get_format.js
@@ -9,7  9,6 @@ const {
   StringPrototypeCharCodeAt,
   StringPrototypeSlice,
 } = primordials;
-const { basename, relative } = require('path');
 const { getOptionValue } = require('internal/options');
 const {
   extensionFormatMap,
@@ -22,7  21,7 @@ const experimentalNetworkImports =
 const defaultTypeFlag = getOptionValue('--experimental-default-type');
 // The next line is where we flip the default to ES modules someday.
 const defaultType = defaultTypeFlag === 'module' ? 'module' : 'commonjs';
-const { getPackageType, getPackageScopeConfig } = require('internal/modules/esm/resolve');
 const { getPackageType } = require('internal/modules/esm/resolve');
 const { fileURLToPath } = require('internal/url');
 const { ERR_UNKNOWN_FILE_EXTENSION } = require('internal/errors').codes;
 
@@ -112,17  111,16 @@ function getFileProtocolModuleFormat(url, context, ignoreErrors) {
     if (defaultType === 'commonjs') { // Legacy behavior
       if (packageType === 'none' || packageType === 'commonjs') {
         return 'commonjs';
-      }
-      // If package type is `module`, fall through to the error case below
-    } else { // Else defaultType === 'module'
-      if (underNodeModules(url)) { // Exception for package scopes under `node_modules`
-        return 'commonjs';
-      }
-      if (packageType === 'none' || packageType === 'module') {
-        return getFormatOfExtensionlessFile(url);
-      } // Else packageType === 'commonjs'
-      return 'commonjs';
       } // Else packageType === 'module'
       return getFormatOfExtensionlessFile(url);
     } // Else defaultType === 'module'
     if (underNodeModules(url)) { // Exception for package scopes under `node_modules`
       return packageType === 'module' ? getFormatOfExtensionlessFile(url) : 'commonjs';
     }
     if (packageType === 'none' || packageType === 'module') {
       return getFormatOfExtensionlessFile(url);
     } // Else packageType === 'commonjs'
     return 'commonjs';
   }
 
   const format = extensionFormatMap[ext];
@@ -131,17  129,7 @@ function getFileProtocolModuleFormat(url, context, ignoreErrors) {
   // Explicit undefined return indicates load hook should rerun format check
   if (ignoreErrors) { return undefined; }
   const filepath = fileURLToPath(url);
-  let suggestion = '';
-  if (getPackageType(url) === 'module' && ext === '') {
-    const config = getPackageScopeConfig(url);
-    const fileBasename = basename(filepath);
-    const relativePath = StringPrototypeSlice(relative(config.pjsonPath, filepath), 1);
-    suggestion = 'Loading extensionless files is not supported inside of "type":"module" package.json contexts '  
-      `without --experimental-default-type=module. The package.json file ${config.pjsonPath} caused this "type":"module" `  
-      `context. Try changing ${filepath} to have a file extension. Note the "bin" field of package.json can point `  
-      `to a file with an extension, for example {"type":"module","bin":{"${fileBasename}":"${relativePath}.js"}}`;
-  }
-  throw new ERR_UNKNOWN_FILE_EXTENSION(ext, filepath, suggestion);
   throw new ERR_UNKNOWN_FILE_EXTENSION(ext, filepath);
 }
 
 /**

diff --git a/test/es-module/test-esm-extensionless-esm-and-wasm.mjs b/test/es-module/test-esm-extensionless-esm-and-wasm.mjs
@@ -0,0  1,106 @@
 // Flags: --experimental-wasm-modules
 import { mustNotCall, spawnPromisified } from '../common/index.mjs';
 import * as fixtures from '../common/fixtures.mjs';
 import { describe, it } from 'node:test';
 import { match, ok, strictEqual } from 'node:assert';
 
 describe('extensionless ES modules within a "type": "module" package scope', { concurrency: true }, () => {
   it('should run as the entry point', async () => {
     const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
       fixtures.path('es-modules/package-type-module/noext-esm'),
     ]);
 
     strictEqual(stderr, '');
     strictEqual(stdout, 'executed\n');
     strictEqual(code, 0);
     strictEqual(signal, null);
   });
 
   it('should be importable', async () => {
     const { default: defaultExport } =
               await import(fixtures.fileURL('es-modules/package-type-module/noext-esm'));
     strictEqual(defaultExport, 'module');
   });
 
   it('should be importable from a module scope under node_modules', async () => {
     const { default: defaultExport } =
       await import(fixtures.fileURL(
         'es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-esm'));
     strictEqual(defaultExport, 'module');
   });
 });
 describe('extensionless Wasm modules within a "type": "module" package scope', { concurrency: true }, () => {
   it('should run as the entry point', async () => {
     const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
       '--experimental-wasm-modules',
       '--no-warnings',
       fixtures.path('es-modules/package-type-module/noext-wasm'),
     ]);
 
     strictEqual(stderr, '');
     strictEqual(stdout, 'executed\n');
     strictEqual(code, 0);
     strictEqual(signal, null);
   });
 
   it('should be importable', async () => {
     const { add } = await import(fixtures.fileURL('es-modules/package-type-module/noext-wasm'));
     strictEqual(add(1, 2), 3);
   });
 
   it('should be importable from a module scope under node_modules', async () => {
     const { add } = await import(fixtures.fileURL(
       'es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-wasm'));
     strictEqual(add(1, 2), 3);
   });
 });
 
 describe('extensionless ES modules within no package scope', { concurrency: true }, () => {
   // This succeeds with `--experimental-default-type=module`
   it('should error as the entry point', async () => {
     const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
       fixtures.path('es-modules/noext-esm'),
     ]);
 
     match(stderr, /SyntaxError/);
     strictEqual(stdout, '');
     strictEqual(code, 1);
     strictEqual(signal, null);
   });
 
   // This succeeds with `--experimental-default-type=module`
   it('should error on import', async () => {
     try {
       await import(fixtures.fileURL('es-modules/noext-esm'));
       mustNotCall();
     } catch (err) {
       ok(err instanceof SyntaxError);
     }
   });
 });
 
 describe('extensionless Wasm within no package scope', { concurrency: true }, () => {
   // This succeeds with `--experimental-default-type=module`
   it('should error as the entry point', async () => {
     const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
       '--experimental-wasm-modules',
       '--no-warnings',
       fixtures.path('es-modules/noext-wasm'),
     ]);
 
     match(stderr, /SyntaxError/);
     strictEqual(stdout, '');
     strictEqual(code, 1);
     strictEqual(signal, null);
   });
 
   // This succeeds with `--experimental-default-type=module`
   it('should error on import', async () => {
     try {
       await import(fixtures.fileURL('es-modules/noext-wasm'));
       mustNotCall();
     } catch (err) {
       ok(err instanceof SyntaxError);
     }
   });
 });
diff --git a/test/es-module/test-esm-type-flag-package-scopes.mjs b/test/es-module/test-esm-type-flag-package-scopes.mjs
@@ -24,6  24,14 @@ describe('the type flag should change the interpretation of certain files within
              strictEqual(defaultExport, 'module');
            });
 
            it('should import an extensionless JavaScript file within a "type": "module" scope under node_modules',
               async () => {
                 const { default: defaultExport } =
                 await import(fixtures.fileURL(
                   'es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-esm'));
                 strictEqual(defaultExport, 'module');
               });
 
            it('should run as Wasm an extensionless Wasm file within a "type": "module" scope', async () => {
              const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
                '--experimental-default-type=module',
@@ -42,6  50,13 @@ describe('the type flag should change the interpretation of certain files within
              const { add } = await import(fixtures.fileURL('es-modules/package-type-module/noext-wasm'));
              strictEqual(add(1, 2), 3);
            });
 
            it('should import an extensionless Wasm file within a "type": "module" scope under node_modules',
               async () => {
                 const { add } = await import(fixtures.fileURL(
                   'es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-wasm'));
                 strictEqual(add(1, 2), 3);
               });
          });
 
 describe(`the type flag should change the interpretation of certain files within a package scope that lacks a
@@ -112,7  127,7 @@ describe(`the type flag should NOT change the interpretation of certain files wi
      async () => {
        const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
          '--experimental-default-type=module',
-         fixtures.path('es-modules/package-type-module/node_modules/dep-with-package-json/run.js'),
          fixtures.path('es-modules/package-type-module/node_modules/dep-with-package-json-without-type/run.js'),
        ]);
 
        strictEqual(stderr, '');
@@ -124,15  139,16 @@ describe(`the type flag should NOT change the interpretation of certain files wi
   it(`should import as CommonJS a .js file within a package scope that has no defined "type" and is under
   node_modules`, async () => {
     const { default: defaultExport } =
-      await import(fixtures.fileURL('es-modules/package-type-module/node_modules/dep-with-package-json/run.js'));
       await import(fixtures.fileURL(
         'es-modules/package-type-module/node_modules/dep-with-package-json-without-type/run.js'));
     strictEqual(defaultExport, 42);
   });
 
   it(`should run as CommonJS an extensionless JavaScript file within a package scope that has no defined "type" and is
   under node_modules`, async () => {
     const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
       '--experimental-default-type=module',
-      fixtures.path('es-modules/package-type-module/node_modules/dep-with-package-json/noext-cjs'),
       fixtures.path('es-modules/package-type-module/node_modules/dep-with-package-json-without-type/noext-cjs'),
     ]);
 
     strictEqual(stderr, '');
@@ -144,7  160,8 @@ describe(`the type flag should NOT change the interpretation of certain files wi
   it(`should import as CommonJS an extensionless JavaScript file within a package scope that has no defined "type" and
   is under node_modules`, async () => {
     const { default: defaultExport } =
-      await import(fixtures.fileURL('es-modules/package-type-module/node_modules/dep-with-package-json/noext-cjs'));
       await import(fixtures.fileURL(
         'es-modules/package-type-module/node_modules/dep-with-package-json-without-type/noext-cjs'));
     strictEqual(defaultExport, 42);
   });
 });
diff --git a/...odule/test-esm-unknown-or-no-extension.js → test/es-module/test-esm-unknown-extension.js b/...odule/test-esm-unknown-or-no-extension.js → test/es-module/test-esm-unknown-extension.js
@@ -7,14  7,11 @@ const { execPath } = require('node:process');
 const { describe, it } = require('node:test');
 
 
-// In a "type": "module" package scope, files with unknown extensions or no
-// extensions should throw; both when used as a main entry point and also when
-// referenced via `import`.
-describe('ESM: extensionless and unknown specifiers', { concurrency: true }, () => {
 // In a "type": "module" package scope, files with unknown extensions should throw;
 // both when used as a main entry point and also when referenced via `import`.
 describe('ESM: unknown specifiers', { concurrency: true }, () => {
   for (
     const fixturePath of [
-      '/es-modules/package-type-module/noext-esm',
-      '/es-modules/package-type-module/imports-noext.mjs',
       '/es-modules/package-type-module/extension.unknown',
       '/es-modules/package-type-module/imports-unknownext.mjs',
     ]
@@ -27,10  24,6 @@ describe('ESM: extensionless and unknown specifiers', { concurrency: true }, ()
       assert.strictEqual(signal, null);
       assert.strictEqual(stdout, '');
       assert.match(stderr, /ERR_UNKNOWN_FILE_EXTENSION/);
-      if (fixturePath.includes('noext')) {
-        // Check for explanation to users
-        assert.match(stderr, /extensionless/);
-      }
     });
   }
 });
diff --git a/...s/es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-esm b/...s/es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-esm
diff --git a/.../es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-wasm b/.../es-modules/package-type-module/node_modules/dep-with-package-json-type-module/noext-wasm
diff --git a/...s-modules/package-type-module/node_modules/dep-with-package-json-type-module/package.json b/...s-modules/package-type-module/node_modules/dep-with-package-json-type-module/package.json
diff --git a/...s-modules/package-type-module/node_modules/dep-with-package-json-type-module/wasm-dep.mjs b/...s-modules/package-type-module/node_modules/dep-with-package-json-type-module/wasm-dep.mjs
diff --git a/...node_modules/dep-with-package-json/dep.js → ...dep-with-package-json-without-type/dep.js b/...node_modules/dep-with-package-json/dep.js → ...dep-with-package-json-without-type/dep.js
diff --git a/...e_modules/dep-with-package-json/noext-cjs → ...-with-package-json-without-type/noext-cjs b/...e_modules/dep-with-package-json/noext-cjs → ...-with-package-json-without-type/noext-cjs
diff --git a/...odules/dep-with-package-json/package.json → ...th-package-json-without-type/package.json b/...odules/dep-with-package-json/package.json → ...th-package-json-without-type/package.json
diff --git a/...node_modules/dep-with-package-json/run.js → ...dep-with-package-json-without-type/run.js b/...node_modules/dep-with-package-json/run.js → ...dep-with-package-json-without-type/run.js