module: unflag esm json modules

PR-URL: #41736
Backport-PR-URL: #42726
Reviewed-By: Antoine du Hamel <[email protected]>
Reviewed-By: Guy Bedford <[email protected]>
Reviewed-By: Mohammed Keyvanzadeh <[email protected]>
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Bradley Farias <[email protected]>

Author: GeoffreyBooth

doc/api/cli.md

@@ -282,14 +282,6 @@ added:
 
 Enable experimental `import.meta.resolve()` support.
 
-### `--experimental-json-modules`
-
-<!-- YAML
-added: v12.9.0
--->
-
-Enable experimental JSON support for the ES Module loader.
-
 ### `--experimental-loader=module`
 
 <!-- YAML

doc/api/esm.md

@@ -471,22 +471,6 @@ These CommonJS variables are not available in ES modules.
 `__filename` and `__dirname` use cases can be replicated via
 [`import.meta.url`][].
 
-#### No JSON Module Loading
-
-JSON imports are still experimental and only supported via the
-`--experimental-json-modules` flag.
-
-Local JSON files can be loaded relative to `import.meta.url` with `fs` directly:
-
-<!-- eslint-skip -->
-
-```js
-import { readFile } from 'fs/promises';
-const json = JSON.parse(await readFile(new URL('./dat.json', import.meta.url)));
-```
-
-Alternatively `module.createRequire()` can be used.
-
 #### No Native Module Loading
 
 Native modules are not currently supported with ES module imports.
@@ -524,35 +508,19 @@ separate cache.
 
 > Stability: 1 - Experimental
 
-Currently importing JSON modules are only supported in the `commonjs` mode
-and are loaded using the CJS loader. [WHATWG JSON modules specification][] are
-still being standardized, and are experimentally supported by including the
-additional flag `--experimental-json-modules` when running Node.js.
-
-When the `--experimental-json-modules` flag is included, both the
-`commonjs` and `module` mode use the new experimental JSON
-loader. The imported JSON only exposes a `default`. There is no
-support for named exports. A cache entry is created in the CommonJS
-cache to avoid duplication. The same object is returned in
-CommonJS if the JSON module has already been imported from the
-same path.
-
-Assuming an `index.mjs` with
+JSON files can be referenced by `import`:
 
 ```js
 import packageConfig from './package.json' assert { type: 'json' };
 ```
 
-The `--experimental-json-modules` flag is needed for the module
-to work.
-
-```bash
-node index.mjs # fails
-node --experimental-json-modules index.mjs # works
-```
-
 The `assert { type: 'json' }` syntax is mandatory; see [Import Assertions][].
 
+The imported JSON only exposes a `default` export. There is no support for named
+exports. A cache entry is created in the CommonJS cache to avoid duplication.
+The same object is returned in CommonJS if the JSON module has already been
+imported from the same path.
+
 <i id="esm_experimental_wasm_modules"></i>
 
 ## Wasm modules
@@ -1467,7 +1435,6 @@ success!
 [Node.js Module Resolution Algorithm]: #resolver-algorithm-specification
 [Terminology]: #terminology
 [URL]: https://url.spec.whatwg.org/
-[WHATWG JSON modules specification]: https://html.spec.whatwg.org/#creating-a-json-module-script
 [`"exports"`]: packages.md#exports
 [`"type"`]: packages.md#type
 [`--input-type`]: cli.md#--input-typetype

doc/api/packages.md

@@ -117,8 +117,7 @@ There is the ECMAScript module loader:
   `'./startup/index.js'`) must be fully specified.
 * It does no extension searching. A file extension must be provided
   when the specifier is a relative or absolute file URL.
-* It can load JSON modules, but an import assertion is required (behind
-  `--experimental-json-modules` flag).
+* It can load JSON modules, but an import assertion is required.
 * It accepts only `.js`, `.mjs`, and `.cjs` extensions for JavaScript text
   files.
 * It can be used to load JavaScript CommonJS modules. Such modules

doc/node.1

@@ -142,9 +142,6 @@ Enable Source Map V3 support for stack traces.
 .It Fl -experimental-import-meta-resolve
 Enable experimental ES modules support for import.meta.resolve().
 .
-.It Fl -experimental-json-modules
-Enable experimental JSON interop support for the ES Module loader.
-.
 .It Fl -experimental-loader Ns = Ns Ar module
 Specify the
 .Ar module

lib/internal/modules/esm/get_format.js

@@ -8,7 +8,6 @@ const {
 const { extname } = require('path');
 const { getOptionValue } = require('internal/options');
 
-const experimentalJsonModules = getOptionValue('--experimental-json-modules');
 const experimentalSpecifierResolution =
   getOptionValue('--experimental-specifier-resolution');
 const experimentalWasmModules = getOptionValue('--experimental-wasm-modules');
@@ -20,7 +19,8 @@ const extensionFormatMap = {
   '__proto__': null,
   '.cjs': 'commonjs',
   '.js': 'module',
-  '.mjs': 'module'
+  '.json': 'json',
+  '.mjs': 'module',
 };
 
 const legacyExtensionFormatMap = {
@@ -29,17 +29,14 @@ const legacyExtensionFormatMap = {
   '.js': 'commonjs',
   '.json': 'commonjs',
   '.mjs': 'module',
-  '.node': 'commonjs'
+  '.node': 'commonjs',
 };
 
 let experimentalSpecifierResolutionWarned = false;
 
 if (experimentalWasmModules)
   extensionFormatMap['.wasm'] = legacyExtensionFormatMap['.wasm'] = 'wasm';
 
-if (experimentalJsonModules)
-  extensionFormatMap['.json'] = legacyExtensionFormatMap['.json'] = 'json';
-
 const protocolHandlers = ObjectAssign(ObjectCreate(null), {
   'data:'(parsed) {
     const { 1: mime } = RegExpPrototypeExec(
@@ -49,7 +46,7 @@ const protocolHandlers = ObjectAssign(ObjectCreate(null), {
     const format = ({
       '__proto__': null,
       'text/javascript': 'module',
-      'application/json': experimentalJsonModules ? 'json' : null,
+      'application/json': 'json',
       'application/wasm': experimentalWasmModules ? 'wasm' : null
     })[mime] || null;
 

src/node_options.cc

@@ -312,19 +312,13 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             kAllowedInEnvironment);
   AddOption("--experimental-abortcontroller", "",
             NoOp{}, kAllowedInEnvironment);
-  AddOption("--experimental-json-modules",
-            "experimental JSON interop support for the ES Module loader",
-            &EnvironmentOptions::experimental_json_modules,
-            kAllowedInEnvironment);
+  AddOption("--experimental-json-modules", "", NoOp{}, kAllowedInEnvironment);
   AddOption("--experimental-loader",
             "use the specified module as a custom loader",
             &EnvironmentOptions::userland_loader,
             kAllowedInEnvironment);
   AddAlias("--loader", "--experimental-loader");
-  AddOption("--experimental-modules",
-            "",
-            &EnvironmentOptions::experimental_modules,
-            kAllowedInEnvironment);
+  AddOption("--experimental-modules", "", NoOp{}, kAllowedInEnvironment);
   AddOption("--experimental-wasm-modules",
             "experimental ES Module support for webassembly modules",
             &EnvironmentOptions::experimental_wasm_modules,

src/node_options.h

@@ -103,8 +103,6 @@ class EnvironmentOptions : public Options {
   std::vector<std::string> conditions;
   std::string dns_result_order;
   bool enable_source_maps = false;
-  bool experimental_json_modules = false;
-  bool experimental_modules = false;
   std::string experimental_specifier_resolution;
   bool experimental_wasm_modules = false;
   bool experimental_import_meta_resolve = false;

test/es-module/test-esm-assertionless-json-import.js

@@ -1,4 +1,4 @@
-// Flags: --experimental-json-modules --experimental-loader ./test/fixtures/es-module-loaders/assertionless-json-import.mjs
+// Flags: --experimental-loader ./test/fixtures/es-module-loaders/assertionless-json-import.mjs
 'use strict';
 const common = require('../common');
 const { strictEqual } = require('assert');

test/es-module/test-esm-data-urls.js

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 'use strict';
 const common = require('../common');
 const assert = require('assert');

test/es-module/test-esm-dynamic-import-assertion.js

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 'use strict';
 const common = require('../common');
 const { strictEqual } = require('assert');

test/es-module/test-esm-dynamic-import-assertion.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 

test/es-module/test-esm-import-assertion-1.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 

test/es-module/test-esm-import-assertion-2.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 

test/es-module/test-esm-import-assertion-3.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 

test/es-module/test-esm-import-assertion-4.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 

test/es-module/test-esm-import-assertion-errors.js

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 'use strict';
 const common = require('../common');
 const { rejects } = require('assert');

test/es-module/test-esm-import-assertion-errors.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { rejects } from 'assert';
 

test/es-module/test-esm-import-json-named-export.mjs

@@ -5,7 +5,6 @@ import { spawn } from 'child_process';
 import { execPath } from 'process';
 
 const child = spawn(execPath, [
-  '--experimental-json-modules',
   path('es-modules', 'import-json-named-export.mjs'),
 ]);
 

test/es-module/test-esm-invalid-data-urls.js

@@ -5,20 +5,14 @@ const assert = require('assert');
 (async () => {
   await assert.rejects(import('data:text/plain,export default0'), {
     code: 'ERR_INVALID_MODULE_SPECIFIER',
-    message:
-      'Invalid module "data:text/plain,export default0" has an unsupported ' +
-      'MIME type "text/plain"',
+    message: 'Invalid module "data:text/plain,export default0" has an unsupported MIME type "text/plain"',
   });
   await assert.rejects(import('data:text/plain;base64,'), {
     code: 'ERR_INVALID_MODULE_SPECIFIER',
-    message:
-      'Invalid module "data:text/plain;base64," has an unsupported ' +
-      'MIME type "text/plain"',
+    message: 'Invalid module "data:text/plain;base64," has an unsupported MIME type "text/plain"',
   });
-  await assert.rejects(import('data:application/json,[]'), {
+  await assert.rejects(import('data:text/css,.error { color: red; }'), {
     code: 'ERR_INVALID_MODULE_SPECIFIER',
-    message:
-      'Invalid module "data:application/json,[]" has an unsupported ' +
-      'MIME type "application/json"',
+    message: 'Invalid module "data:text/css,.error { color: red; }" has an unsupported MIME type "text/css"',
   });
 })().then(common.mustCall());

test/es-module/test-esm-json-cache.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 
 import { strictEqual, deepStrictEqual } from 'assert';

test/es-module/test-esm-json.mjs

@@ -1,4 +1,3 @@
-// Flags: --experimental-json-modules
 import '../common/index.mjs';
 import { path } from '../common/fixtures.mjs';
 import { strictEqual, ok } from 'assert';
@@ -10,7 +9,6 @@ strictEqual(secret.ofLife, 42);
 
 // Test warning message
 const child = spawn(process.execPath, [
-  '--experimental-json-modules',
   path('/es-modules/json-modules.mjs'),
 ]);
 

test/es-module/test-esm-non-js.js

@@ -0,0 +1,23 @@
+import { mustCall } from '../common/index.mjs';
+import { fileURL } from '../common/fixtures.mjs';
+import { match, strictEqual } from 'assert';
+import { spawn } from 'child_process';
+import { execPath } from 'process';
+
+// Verify non-js extensions fail for ESM
+const child = spawn(execPath, [
+  '--input-type=module',
+  '--eval',
+  `import ${JSON.stringify(fileURL('es-modules', 'file.unknown'))}`,
+]);
+
+let stderr = '';
+child.stderr.setEncoding('utf8');
+child.stderr.on('data', (data) => {
+  stderr += data;
+});
+child.on('close', mustCall((code, signal) => {
+  strictEqual(code, 1);
+  strictEqual(signal, null);
+  match(stderr, /ERR_UNKNOWN_FILE_EXTENSION/);
+}));