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0b9249e335
This patch implements a "module-sync" exports condition
for packages to supply a sycnrhonous ES module to the
Node.js module loader, no matter it's being required
or imported. This is similar to the "module" condition
that bundlers have been using to support `require(esm)`
in Node.js, and allows dual-package authors to opt into
ESM-first only newer versions of Node.js that supports
require(esm) while avoiding the dual-package hazard.
```json
{
"type": "module",
"exports": {
"node": {
// On new version of Node.js, both require() and import get
// the ESM version
"module-sync": "./index.js",
// On older version of Node.js, where "module" and
// require(esm) are not supported, use the transpiled CJS version
// to avoid dual-package hazard. Library authors can decide
// to drop support for older versions of Node.js when they think
// it's time.
"default": "./dist/index.cjs"
},
// On any other environment, use the ESM version.
"default": "./index.js"
}
}
```
We end up implementing a condition with a different name
instead of reusing "module", because existing code in the
ecosystem using the "module" condition sometimes also expect
the module resolution for these ESM files to work in CJS
style, which is supported by bundlers, but the native
Node.js loader has intentionally made ESM resolution
different from CJS resolution (e.g. forbidding `import
'./noext'` or `import './directory'`), so it would be
semver-major to implement a `"module"` condition
without implementing the forbidden ESM resolution rules.
For now, this just implments a new condition as semver-minor
so it can be backported to older LTS.
Refs: https://webpack.js.org/guides/package-exports/#target-environment-independent-packages
PR-URL: https://github.com/nodejs/node/pull/54648
Fixes: https://github.com/nodejs/node/issues/52173
Refs: https://github.com/joyeecheung/test-module-condition
Refs: https://github.com/nodejs/node/issues/52697
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
30 lines
1.2 KiB
JavaScript
30 lines
1.2 KiB
JavaScript
// Flags: --experimental-require-module
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import '../common/index.mjs';
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import assert from 'node:assert';
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import * as staticImport from '../fixtures/es-modules/module-condition/import.mjs';
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import { import as _import } from '../fixtures/es-modules/module-condition/dynamic_import.js';
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async function dynamicImport(id) {
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const result = await _import(id);
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return result.resolved;
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}
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assert.deepStrictEqual({ ...staticImport }, {
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import_module_require: 'import',
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module_and_import: 'module',
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module_and_require: 'module',
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module_import_require: 'module',
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module_only: 'module',
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module_require_import: 'module',
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require_module_import: 'module',
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});
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assert.strictEqual(await dynamicImport('import-module-require'), 'import');
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assert.strictEqual(await dynamicImport('module-and-import'), 'module');
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assert.strictEqual(await dynamicImport('module-and-require'), 'module');
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assert.strictEqual(await dynamicImport('module-import-require'), 'module');
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assert.strictEqual(await dynamicImport('module-only'), 'module');
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assert.strictEqual(await dynamicImport('module-require-import'), 'module');
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assert.strictEqual(await dynamicImport('require-module-import'), 'module');
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