2021-03-03
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#node
Alexander Nnakwue
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Mar 3, 2021 ⋅ 13 min read

Using ES modules in Node.js

Alexander Nnakwue Software engineer. React, Node.js, Python, and other developer tools and libraries.

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4 Replies to "Using ES modules in Node.js"

  1. What about the performance decrease because of the esm modules resolution? I experienced a noticeable difference in the startup between the 13.1 and 13.7 versions (around 20%). I find this huge since I’m not using this feature anywhere yet.

  2. Hello Gergo, I haven’t seen any real life overhead in terms of performance in the new ESM resolution algorithm. Can you point me to how you got the stat you have mentioned above, and since this is not a known issue in the wide, also peeking at the issues tab in the source code (https://github.com/nodejs/node/issues?q=is%3Aissue+is%3Aopen+esm) does not point any issues relating to performance… You can learn more about the ESM algorithm here on the docs, https://nodejs.org/api/esm.html#esm_resolution_algorithm

  3. Hi Alexander,
    Thanks for checking. I couldn’t create a trustworthy benchmark, that’s why I asked. Using 13.8 I don’t see any big differences now.

  4. So how can you _usefully_ import an ES module into a CommonJS module? You make mention of dynamic import but that’s asynchronous and can only be called inside a function which means you can’t import anything into the top level with it since no top level ‘await’.

    Without an elegant solution to that basic interoperability it seems quite painful. I’m not an experienced JS developer and just getting Jasmine to run some tests against an ES module seems like an almighty undocumented ballache. I’ve spent more time trying to make sense of this than actually doing any work!

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