tsc-esm-fix

Make tsc-compiled `es2020/esnext` bundles compatible with esm/mjs requirements

Usage no npm install needed!

<script type="module">
  import tscEsmFix from 'https://cdn.skypack.dev/tsc-esm-fix';
</script>

README

tsc-esm-fix

Make TS projects compatible with esm/mjs requirements

CI Maintainability Test Coverage npm (tag)

Problem

This workaround is aimed to bypass a pair of tsc and ts-jest issues right here and right now.

Solutions

  1. Post-process tsc-compiled outputs everytime after the build.
  2. Patch project sources once as Sindre recommends in ESM migration guide

This lib may be applied in both cases.

Features

  • Injects extensions to imports/re-exports statements.
  • Follows outDir found in tsconfig.json.
  • Searches and replaces __dirname and __filename refs with import.meta.
  • Changes file extensions (applied to local deps only).
  • Supports Windows-based runtimes.

Getting started

Requirements

Node.js ^12.20.0 || ^14.13.1 || >=16.0.0

Install

yarn add -D tsc-esm-fix

Usage examples

tsc-esm-fix [options]

# to post-process outputs each time
tsc-esm-fix --target='target/es6'

# to patch ts sources once
tsc-esm-fix --target='src/main/ts' --ext='.js'

import { fix } from 'tsc-esm-fix'
await fix({
  dirnameVar: true,
  filenameVar: true,
  ext: true
})

Input
code ref

import { foo } from './foo';
import './bar';

// external cjs module
import * as e1def from 'e1/a/b/c';
import * as e1root from 'e1';
const { e1 } = e1def;
const { e1: e1x } = e1root;
export { e1, e1x };

// external esm module with `main` in pkg.json
export { m1 } from 'm1';
export { m1 as m1x } from 'm1/index';

// external esm module with `exports` in pkg.json
export { e2 } from 'e2';
export { e2 as es3 } from 'e2/index';
export { e2 as es4 } from 'e2/alias';
export { e2foo } from 'e2/foo';
export { e2bar } from 'e2/bar-bundle';

export * from './foo';
export * from './baz';
export * from './q/u/x';
export const foobaz = foo + 'baz';
export { foo as foo1 } from './foo.js';

// Dir with index.js file inside: ./qux.js/index.js
export { qux } from './qux.js';

export const dirname = __dirname;
export const filename = __filename;

console.log(foobaz);

Output

import { foo } from './foo.js';
import './bar.js';

import * as e1def from 'e1/a/b/c/index.js';
import * as e1root from 'e1';
const { e1 } = e1def;
const { e1: e1x } = e1root;
export { e1, e1x };

export { m1 } from 'm1';
export { m1 as m1x } from 'm1/index.js';

export { e2 } from 'e2';
export { e2 as es3 } from 'e2/index';
export { e2 as es4 } from 'e2/alias';
export { e2foo } from 'e2/foo';
export { e2bar } from 'e2/bar-bundle';

export * from './foo.js';
export * from './baz/index.js';
export * from './q/u/x/index.js';
export const foobaz = foo + 'baz';
export { foo as foo1 } from './foo.js';

export { qux } from './qux.js/index.js';

export const dirname = /file:\\\\/\\\\/(.+)\\\\/[^/]/.exec(import.meta.url)[1];
export const filename = /file:\\\\/\\\\/(.+)/.exec(import.meta.url)[1];

CLI

tsc-esm-fix [opts]
Option Description Default
--tsconfig Path to project's ts-config(s) tsconfig.json
--src Entry points where the ts-source files are placed. If defined src option suppresses target
--target tsc-compiled output directory If not specified inherited from tsconfig.json compilerOptions.outDir
--dirnameVar Replace __dirname usages with import.meta true
--filenameVar Replace __filename var references with import.meta statements true
--ext Append extension to relative imports/re-exports .js
--unlink Remove original files if ext changes true
--cwd cwd process.cwd()
--out Output dir. Defaults to cwd, so files would be overwritten process.cwd()
--debug Prints debug notes

JS/TS API

import { fix, IFixOptions } from 'tsc-esm-fix'

const fixOptions: IFixOptions = {
  tsconfig: 'tsconfig.build.json',
  dirnameVar: true,
  filenameVar: true,
  ext: true
}

await fix(fixOptions)

export interface IFixOptions {
  cwd: string
  src?: string | string[]
  target?: string | string[]
  out?: string
  tsconfig?: string | string[]
  dirnameVar: boolean
  filenameVar: boolean
  ext: boolean | string
  unlink?: boolean,
  debug?: boolean | IFunction
}

Alternatives

Contributing

Feel free to open any issues: bug reports, feature requests or questions. You're always welcome to suggest a PR. Just fork this repo, write some code, add some tests and push your changes. Any feedback is appreciated.

References

License

MIT