+173
-12
lines changedFilter options
+173
-12
lines changed Original file line number Diff line number Diff line change
@@ -396,6 +396,35 @@ import { readFileSync } from 'node:fs';
396 396
const buffer = readFileSync(new URL('./data.proto', import.meta.url));
397 397
```
398 398 399 +
### `import.meta.main`
400 + 401 +
<!-- YAML
402 +
added:
403 +
- REPLACEME
404 +
-->
405 + 406 +
> Stability: 1.0 - Early development
407 + 408 +
* {boolean} `true` when the current module is the entry point of the current process; `false` otherwise.
409 + 410 +
Equivalent to `require.main === module` in CommonJS.
411 + 412 +
Analogous to Python's `__name__ == "__main__"`.
413 + 414 +
```js
415 +
export function foo() {
416 +
return 'Hello, world';
417 +
}
418 + 419 +
function main() {
420 +
const message = foo();
421 +
console.log(message);
422 +
}
423 + 424 +
if (import.meta.main) main();
425 +
// `foo` can be imported from another module without possible side-effects from `main`
426 +
```
427 + 399 428
### `import.meta.resolve(specifier)`
400 429 401 430
<!-- YAML
@@ -612,6 +641,10 @@ These CommonJS variables are not available in ES modules.
612 641
They can instead be loaded with [`module.createRequire()`][] or
613 642
[`process.dlopen`][].
614 643 644 +
#### No `require.main`
645 + 646 +
To replace `require.main === module`, there is the [`import.meta.main`][] API.
647 + 615 648
#### No `require.resolve`
616 649 617 650
Relative resolution can be handled via `new URL('./local', import.meta.url)`.
@@ -1177,6 +1210,7 @@ resolution for ESM specifiers is [commonjs-extension-resolution-loader][].
1177 1210
[`import()`]: #import-expressions
1178 1211
[`import.meta.dirname`]: #importmetadirname
1179 1212
[`import.meta.filename`]: #importmetafilename
1213 +
[`import.meta.main`]: #importmetamain
1180 1214
[`import.meta.resolve`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import.meta/resolve
1181 1215
[`import.meta.url`]: #importmetaurl
1182 1216
[`import`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import
@@ -203,6 +203,20 @@ port.on('message', (message) => {
203 203
break;
204 204
}
205 205 206 +
case 'data-url': {
207 +
const { runEntryPointWithESMLoader } = require('internal/modules/run_main');
208 + 209 +
RegExpPrototypeExec(/^/, ''); // Necessary to reset RegExp statics before user code runs.
210 +
const promise = runEntryPointWithESMLoader((cascadedLoader) => {
211 +
return cascadedLoader.import(filename, undefined, { __proto__: null }, undefined, true);
212 +
});
213 + 214 +
PromisePrototypeThen(promise, undefined, (e) => {
215 +
workerOnGlobalUncaughtException(e, true);
216 +
});
217 +
break;
218 +
}
219 + 206 220
default: {
207 221
// script filename
208 222
// runMain here might be monkey-patched by users in --require.
@@ -51,12 +51,12 @@ function createImportMetaResolve(defaultParentURL, loader, allowParentURL) {
51 51
/**
52 52
* Create the `import.meta` object for a module.
53 53
* @param {object} meta
54 -
* @param {{url: string}} context
54 +
* @param {{url: string, isMain?: boolean}} context
55 55
* @param {typeof import('./loader.js').ModuleLoader} loader Reference to the current module loader
56 56
* @returns {{dirname?: string, filename?: string, url: string, resolve?: Function}}
57 57
*/
58 58
function initializeImportMeta(meta, context, loader) {
59 -
const { url } = context;
59 +
const { url, isMain } = context;
60 60 61 61
// Alphabetical
62 62
if (StringPrototypeStartsWith(url, 'file:') === true) {
@@ -65,6 +65,8 @@ function initializeImportMeta(meta, context, loader) {
65 65
setLazyPathHelpers(meta, url);
66 66
}
67 67 68 +
meta.main = !!isMain;
69 + 68 70
if (!loader || loader.allowImportMetaResolve) {
69 71
meta.resolve = createImportMetaResolve(url, loader, experimentalImportMetaResolve);
70 72
}
@@ -248,10 +248,11 @@ class ModuleLoader {
248 248
*
249 249
* @param {string} source Source code of the module.
250 250
* @param {string} url URL of the module.
251 +
* @param {{ isMain?: boolean }|undefined} context - context object containing module metadata.
251 252
* @returns {object} The module wrap object.
252 253
*/
253 -
createModuleWrap(source, url) {
254 -
return compileSourceTextModule(url, source, this);
254 +
createModuleWrap(source, url, context = kEmptyObject) {
255 +
return compileSourceTextModule(url, source, this, context);
255 256
}
256 257 257 258
/**
@@ -289,7 +290,8 @@ class ModuleLoader {
289 290
* @returns {Promise<object>} The module object.
290 291
*/
291 292
eval(source, url, isEntryPoint = false) {
292 -
const wrap = this.createModuleWrap(source, url);
293 +
const context = isEntryPoint ? { isMain: true } : undefined;
294 +
const wrap = this.createModuleWrap(source, url, context);
293 295
return this.executeModuleJob(url, wrap, isEntryPoint);
294 296
}
295 297
@@ -103,7 +103,8 @@ translators.set('module', function moduleStrategy(url, source, isMain) {
103 103
source = stringify(source);
104 104
debug(`Translating StandardModule ${url}`);
105 105
const { compileSourceTextModule } = require('internal/modules/esm/utils');
106 -
const module = compileSourceTextModule(url, source, this);
106 +
const context = isMain ? { isMain } : undefined;
107 +
const module = compileSourceTextModule(url, source, this, context);
107 108
return module;
108 109
});
109 110
@@ -42,6 +42,7 @@ const {
42 42
const {
43 43
emitExperimentalWarning,
44 44
getCWDURL,
45 +
kEmptyObject,
45 46
} = require('internal/util');
46 47
const assert = require('internal/assert');
47 48
const {
@@ -188,7 +189,7 @@ function registerModule(referrer, registry) {
188 189
*/
189 190
function defaultInitializeImportMetaForModule(meta, wrap) {
190 191
const cascadedLoader = require('internal/modules/esm/loader').getOrInitializeCascadedLoader();
191 -
return cascadedLoader.importMetaInitialize(meta, { url: wrap.url });
192 +
return cascadedLoader.importMetaInitialize(meta, { url: wrap.url, isMain: wrap.isMain });
192 193
}
193 194 194 195
/**
@@ -342,15 +343,22 @@ async function initializeHooks() {
342 343
* @param {string} source Source code of the module.
343 344
* @param {typeof import('./loader.js').ModuleLoader|undefined} cascadedLoader If provided,
344 345
* register the module for default handling.
346 +
* @param {{ isMain?: boolean }|undefined} context - context object containing module metadata.
345 347
* @returns {ModuleWrap}
346 348
*/
347 -
function compileSourceTextModule(url, source, cascadedLoader) {
349 +
function compileSourceTextModule(url, source, cascadedLoader, context = kEmptyObject) {
348 350
const hostDefinedOption = cascadedLoader ? source_text_module_default_hdo : undefined;
349 351
const wrap = new ModuleWrap(url, undefined, source, 0, 0, hostDefinedOption);
350 352 351 353
if (!cascadedLoader) {
352 354
return wrap;
353 355
}
356 + 357 +
const { isMain } = context;
358 +
if (isMain) {
359 +
wrap.isMain = true;
360 +
}
361 + 354 362
// Cache the source map for the module if present.
355 363
if (wrap.sourceMapURL) {
356 364
maybeCacheSourceMap(url, source, wrap, false, undefined, wrap.sourceMapURL);
@@ -7,7 +7,6 @@ const {
7 7
AtomicsAdd,
8 8
Float64Array,
9 9
FunctionPrototypeBind,
10 -
JSONStringify,
11 10
MathMax,
12 11
ObjectEntries,
13 12
Promise,
@@ -167,8 +166,8 @@ class Worker extends EventEmitter {
167 166
doEval = 'classic';
168 167
} else if (isURL(filename) && filename.protocol === 'data:') {
169 168
url = null;
170 -
doEval = 'module';
171 -
filename = `import ${JSONStringify(`${filename}`)}`;
169 +
doEval = 'data-url';
170 +
filename = `${filename}`;
172 171
} else {
173 172
doEval = false;
174 173
if (isURL(filename)) {
@@ -0,0 +1,74 @@
1 +
import { spawnPromisified } from '../common/index.mjs';
2 +
import * as fixtures from '../common/fixtures.js';
3 +
import assert from 'node:assert/strict';
4 +
import { describe, it } from 'node:test';
5 + 6 +
const importMetaMainScript = `
7 +
import assert from 'node:assert/strict';
8 + 9 +
assert.strictEqual(import.meta.main, true, 'import.meta.main should evaluate true in main module');
10 + 11 +
const { isMain: importedModuleIsMain } = await import(
12 +
${JSON.stringify(fixtures.fileURL('es-modules/import-meta-main.mjs'))}
13 +
);
14 +
assert.strictEqual(importedModuleIsMain, false, 'import.meta.main should evaluate false in imported module');
15 +
`;
16 + 17 +
function wrapScriptInEvalWorker(script) {
18 +
return `
19 +
import { Worker } from 'node:worker_threads';
20 +
new Worker(${JSON.stringify(script)}, { eval: true });
21 +
`;
22 +
}
23 + 24 +
function convertScriptSourceToDataUrl(script) {
25 +
return new URL(`data:text/javascript,${encodeURIComponent(script)}`);
26 +
}
27 + 28 +
function wrapScriptInUrlWorker(script) {
29 +
return `
30 +
import { Worker } from 'node:worker_threads';
31 +
new Worker(new URL(${JSON.stringify(convertScriptSourceToDataUrl(script))}));
32 +
`;
33 +
}
34 + 35 +
describe('import.meta.main in evaluated scripts', () => {
36 +
it('should evaluate true in evaluated script', async () => {
37 +
const result = await spawnPromisified(
38 +
process.execPath,
39 +
['--input-type=module', '--eval', importMetaMainScript],
40 +
);
41 +
assert.deepStrictEqual(result, {
42 +
stderr: '',
43 +
stdout: '',
44 +
code: 0,
45 +
signal: null,
46 +
});
47 +
});
48 + 49 +
it('should evaluate true in worker instantiated with module source by evaluated script', async () => {
50 +
const result = await spawnPromisified(
51 +
process.execPath,
52 +
['--input-type=module', '--eval', wrapScriptInEvalWorker(importMetaMainScript)],
53 +
);
54 +
assert.deepStrictEqual(result, {
55 +
stderr: '',
56 +
stdout: '',
57 +
code: 0,
58 +
signal: null,
59 +
});
60 +
});
61 + 62 +
it('should evaluate true in worker instantiated with `data:` URL by evaluated script', async () => {
63 +
const result = await spawnPromisified(
64 +
process.execPath,
65 +
['--input-type=module', '--eval', wrapScriptInUrlWorker(importMetaMainScript)],
66 +
);
67 +
assert.deepStrictEqual(result, {
68 +
stderr: '',
69 +
stdout: '',
70 +
code: 0,
71 +
signal: null,
72 +
});
73 +
});
74 +
});
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
1 +
import '../common/index.mjs';
2 +
import assert from 'node:assert/strict';
3 +
import { Worker } from 'node:worker_threads';
4 + 5 +
function get_environment() {
6 +
if (process.env.HAS_STARTED_WORKER) return 'in worker thread started by ES Module';
7 +
return 'in ES Module';
8 +
}
9 + 10 +
assert.strictEqual(
11 +
import.meta.main,
12 +
true,
13 +
`\`import.meta.main\` at top-level module ${get_environment()} should evaluate \`true\``
14 +
);
15 + 16 +
const { isMain: importedModuleIsMain } = await import('../fixtures/es-modules/import-meta-main.mjs');
17 +
assert.strictEqual(
18 +
importedModuleIsMain,
19 +
false,
20 +
`\`import.meta.main\` at dynamically imported module ${get_environment()} should evaluate \`false\``
21 +
);
22 + 23 +
if (!process.env.HAS_STARTED_WORKER) {
24 +
process.env.HAS_STARTED_WORKER = 1;
25 +
new Worker(import.meta.filename);
26 +
}
Original file line number Diff line number Diff line change
@@ -3,7 +3,7 @@ import assert from 'assert';
3 3 4 4
assert.strictEqual(Object.getPrototypeOf(import.meta), null);
5 5 6 -
const keys = ['dirname', 'filename', 'resolve', 'url'];
6 +
const keys = ['dirname', 'filename', 'main', 'resolve', 'url'];
7 7
assert.deepStrictEqual(Reflect.ownKeys(import.meta), keys);
8 8 9 9
const descriptors = Object.getOwnPropertyDescriptors(import.meta);
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