node/test/fixtures/es-modules/export-es-module.mjs

export const __esModule = 'test';
export default { hello: 'world' };
module: add __esModule to require()'d ESM Tooling in the ecosystem have been using the __esModule property to recognize transpiled ESM in consuming code. For example, a 'log' package written in ESM: export function log(val) { console.log(val); } Can be transpiled as: exports.__esModule = true; exports.default = function log(val) { console.log(val); } The consuming code may be written like this in ESM: import log from 'log' Which gets transpiled to: const _mod = require('log'); const log = _mod.__esModule ? _mod.default : _mod; So to allow transpiled consuming code to recognize require()'d real ESM as ESM and pick up the default exports, we add a __esModule property by building a source text module facade for any module that has a default export and add .__esModule = true to the exports. We don't do this to modules that don't have default exports to avoid the unnecessary overhead. This maintains the enumerability of the re-exported names and the live binding of the exports. The source of the facade is defined as a constant per-isolate property required_module_facade_source_string, which looks like this export * from 'original'; export { default } from 'original'; export const __esModule = true; And the 'original' module request is always resolved by createRequiredModuleFacade() to wrap which is a ModuleWrap wrapping over the original module. PR-URL: https://github.com/nodejs/node/pull/52166 Refs: https://github.com/nodejs/node/issues/52134 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Filip Skokan <panva.ip@gmail.com> Reviewed-By: Chengzhong Wu <legendecas@gmail.com> Reviewed-By: Guy Bedford <guybedford@gmail.com> Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com> 2024-03-20 20:41:22 +00:00			`export const __esModule = 'test';`
			`export default { hello: 'world' };`