node/test/es-module/test-require-module-twice.js

// Flags: --experimental-require-module
'use strict';

require('../common');
const assert = require('assert');

const modules = [
  '../fixtures/es-module-loaders/module-named-exports.mjs',
  '../fixtures/es-modules/import-esm.mjs',
  '../fixtures/es-modules/require-cjs.mjs',
  '../fixtures/es-modules/cjs-exports.mjs',
  '../common/index.mjs',
  '../fixtures/es-modules/package-type-module/index.js',
];

for (const id of modules) {
  const first = require(id);
  const second = require(id);
  assert.strictEqual(first, second,
                     `the results of require('${id}') twice are not reference equal`);
}
module: support require()ing synchronous ESM graphs This patch adds `require()` support for synchronous ESM graphs under the flag `--experimental-require-module` This is based on the the following design aspect of ESM: - The resolution can be synchronous (up to the host) - The evaluation of a synchronous graph (without top-level await) is also synchronous, and, by the time the module graph is instantiated (before evaluation starts), this is is already known. If `--experimental-require-module` is enabled, and the ECMAScript module being loaded by `require()` meets the following requirements: - Explicitly marked as an ES module with a `"type": "module"` field in the closest package.json or a `.mjs` extension. - Fully synchronous (contains no top-level `await`). `require()` will load the requested module as an ES Module, and return the module name space object. In this case it is similar to dynamic `import()` but is run synchronously and returns the name space object directly. ```mjs // point.mjs export function distance(a, b) { return (b.x - a.x) 2 + (b.y - a.y) 2; } class Point { constructor(x, y) { this.x = x; this.y = y; } } export default Point; ``` ```cjs const required = require('./point.mjs'); // [Module: null prototype] { // default: [class Point], // distance: [Function: distance] // } console.log(required); (async () => { const imported = await import('./point.mjs'); console.log(imported === required); // true })(); ``` If the module being `require()`'d contains top-level `await`, or the module graph it `import`s contains top-level `await`, [`ERR_REQUIRE_ASYNC_MODULE`][] will be thrown. In this case, users should load the asynchronous module using `import()`. If `--experimental-print-required-tla` is enabled, instead of throwing `ERR_REQUIRE_ASYNC_MODULE` before evaluation, Node.js will evaluate the module, try to locate the top-level awaits, and print their location to help users fix them. PR-URL: https://github.com/nodejs/node/pull/51977 Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Guy Bedford <guybedford@gmail.com> Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com> Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com> 2024-03-11 17:50:24 +00:00			`// Flags: --experimental-require-module`
			`'use strict';`

			`require('../common');`
			`const assert = require('assert');`

			`const modules = [`
			`'../fixtures/es-module-loaders/module-named-exports.mjs',`
			`'../fixtures/es-modules/import-esm.mjs',`
			`'../fixtures/es-modules/require-cjs.mjs',`
			`'../fixtures/es-modules/cjs-exports.mjs',`
			`'../common/index.mjs',`
			`'../fixtures/es-modules/package-type-module/index.js',`
			`];`

			`for (const id of modules) {`
			`const first = require(id);`
			`const second = require(id);`
			`assert.strictEqual(first, second,`
			`the results of require('${id}') twice are not reference equal`);
			`}`