esm: unflag extensionless ES module JavaScript and Wasm in module scope

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**.

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);

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' ? 'module' : '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);
 }
 
 /**

test/es-module/test-esm-extensionless-esm-and-wasm.mjs

@@ -0,0 +1,99 @@
+// 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);
+ });
+});
+
+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);
+ }
+ });
+});

test/es-module/test-esm-type-flag-package-scopes.mjs

@@ -24,6 +24,12 @@
  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',
@@ -112,7 +118,7 @@
  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 +130,15 @@
  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 +150,7 @@
  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);
  });
 });

test/es-module/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/);
- }
  });
  }
 });