`Error [ERR_REQUIRE_ESM]`: Must use import to load ES Module: `ROOT\node_modules\camelcase-keys\index.js` about camelcase-keys

[sindresorhus]

https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[simplenotezy]

I ended up simply using:

_.mapKeys(obj, (v, k) => _.camelCase(k))

Since importing the package was not easily possible with Nest.js unfortunately

[isaachinman]

Hello all. I've created a util to convert ESM-only packages to CJS, for those who need it. This is still very much a work in progress, so please open an issue on the repository with any feedback.

This package ([email protected]) can be installed as CJS via @cjs-exporter/camelcase-keys.

[simplenotezy]

@sindresorhus How would this work with Nest.js

[GeylanKalafMohe]

I ended up simply using:

_.mapKeys(obj, (v, k) => _.camelCase(k))

Since importing the package was not easily possible with Nest.js unfortunately

What is "_" and obj here?

[freddygarcia]

I ended up simply using:

_.mapKeys(obj, (v, k) => _.camelCase(k))

Since importing the package was not easily possible with Nest.js unfortunately

What is "_" and obj here?

@GeylanKalafMohe Lodash

[akay64]

Because I wanted to use the latest version of this library I used an approach where I used ESBuild to convert this ESM only lib to CJS format. This should work for most of such cases and ideally you wont have to do this often as there aren't many libraries that have removed CJS support. In addition to that doing this for these type small util libraries, you likely don't really need to update ever them unless there is some serious security issue in which case you can use repeat the process again.

So I ran ESBuild, took the built result and the index.d.ts file, put it into a "vendor" directory and import from there. Problem solved if you don't want to migrate off of CJS if your project already works that way. It took 5 to 10 mins max and got back on track.

1. npm install esbuild
2. git clone repo of the ESM lib you want to use that does not offer CJS support in this case to ./camelcase-keys
3. open package.json of that repo
4. remove the line "type": "module"
5. Remove "exports": { "types": "./index.d.ts", "default": "./index.js" }
6. Add "types": "./index.d.ts" and "main": "./index.js"
7. npx esbuild ./camelcase-keys --bundle --platform="node" --outfile=./static-vendor/camelcase-keys/index.js
8. import and use in your code like normal import camelcaseKeys from "../static-vendor/camelcase-keys/index.js";
9. Copy index.d.ts file from cloned repo to ./static-vendor/camelcase-keys/

If you want you can probably alias it or something and make the import cleaner but this is fine for my needs, typing also works perfectly.

Cheers.