ESM-ify paths

Rewrites relative paths in import and export statements to be fully qualified.

Why?

It has turned out to be quite tricky to write valid esm code with TS due to the requirement of fully qualified filenames.

With this tool you continue writing TS like you always have--without specifying file extension in import and export paths.

How

Regardless of tooling, assume a structure similar to this:

app/
├─ dist/
│  ├─ cjs/
│  │  ├─ index.js
│  │  ├─ ...
│  ├─ esm/
│  │  ├─ index.js
│  │  ├─ ...

Because both cjs and esm have the same file extensions (.js) one of them needs an package.json to override the root's package.json#module.

If the root is commonjs, add this package.json in dist/esm.

{
  "type": "module"
}

Now you're ready to run esmify-paths on dist/esm, which will make sure all relative paths in js files have an .js extension.

Under the hood it uses require.resolve which means it's also able to resolve imports to directories (by appending /index.js).

Usage CLI

npx esmify-paths [options] input1 input2...

Flags

• --dry: dry run. Default false.
• --verbose: verbose output, possibly useful when debugging. Default false.

Usage node

import { esmify } from 'esmify-paths';

// inputs: string[]
// options?: { dry?: boolean; verbose?: boolean; }
const result = await esmify(inputs, options);