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ES modules are still reasonably new in Node.js land (they're stable since Node 14). Modules come with a built-in module system and features such as top-level await.

I read an informative post on ES modules by Pawel Grzybek and learned that you can't import JSON files in ES modules today. That's a real bummer because I'm pretty used to doing const data = require('./some-file.json') in Node.js.

While it will be possible to eventually import JSON from within modules, the implementation is still behind a feature flag (--experimental-json-modules).

/* 
  Experimental JSON import is behind a flag
  $ node index.mjs # doesn't work
  $ node --experimental-json-modules index.mjs #works
*/

// index.mjs
import packageConfig from './package.json';

This post explains ways to deal with JSON in ES modules today.

Option 1: Read and parse JSON files yourself

The Node.js documentation advises to use the fs module and do the work of reading the files and parsing it yourself.

import { readFile } from 'fs/promises';
const json = JSON.parse(
  await readFile(
    new URL('./some-file.json', import.meta.url)
  )
);

Option 2: Leverage the CommonJS require function to load JSON files

The documentation also states that you can use createRequire to load JSON files. This approach is the way Pawel advises in his blog post.

createRequire allows you to construct a CommonJS require function so that you can use typical CommonJS features such as reading JSON in your Node.js EcmaScript modules.

import { createRequire } from "module";
const require = createRequire(import.meta.url);
const data = require("./data.json");

How should you load JSON files?

I don't know. 🤷‍♂️ Neither option feels good, and I'll probably stick to the first option because it's more understandable.

Let's see when stable JSON modules land in Node.js and if there won't be a change of plans because Import Assertions are coming, too.

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