Brian De Sousa
Jul 22, 2019 ⋅ 5 min read

ES modules in Node.js 12, from experimental to release

Brian De Sousa Geek. Dad. Husband. Developer. Traveler.

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5 Replies to "ES modules in Node.js 12, from experimental to release"

  1. Thank you for clarification! And one question is still not covered: why .mjs? Does it mean we should have both identical. js and mjs files in a package for browsers/babel and node?

  2. From what I understand, NodeJS developers considered several options for being able to suppor ES modules alongside existing CommonJS modules including not using the .mjs extension. At the end of the day, I believe the decision was made to use the .mjs extension because it was a simply way to identify an ES module over plain JavaScript or CommonJS modules. It also sort of fits in the JavaScript community with other frameworks and tools using file extensions as meta-data (ex. typescript uses .ts, react has .jsx, etc.). Here’s a great write up on other options that were considered: https://2ality.com/2017/05/es-module-specifiers.html.

    Browsers will be able to load modules from .mjs files as well but the .mjs extension will not identify that a script contains an ES module. In the browser, you’ll need to include the type=”module” attribute on your script tags, for example:


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