tsc-esm-fix

tsc-esm-fix

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

Motivation

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

• TS/13422 / TS/16577: tsc should add .js extensions for relative module paths.
• ts-jest/1174: import.meta is not allowed.

Hope one day this library will not be needed.

Features

• Injects extensions to imports/re-exports statements.
  • import {foo} from './foo' → import {foo} from './foo.js'
  • import {baz} from 'external/baz' → import {baz} from 'external/baz.js'
  • Note, including the file extension is only necessary for packages without an "exports" field. So in this case all the external refs remain as are.
  • Pays attention to index files: import {bar} from './bar' → import {bar} from './bar/index.js'
• Follows outDir found in tsconfig.json.
• Finds and replaces __dirname and __filename refs with import.meta.
• Changes file extensions (applied to local deps only).
• Supports Windows-based runtimes.

Requirements

Node.js >= 14

Install

yarn add -D tsc-esm-fix

Usage

tsc-esm-fix [options]

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.file ./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];

API

CLI

tsc-esm-fix [opts]

Option	Description	Default
--tsconfig	Path to project's ts-config(s)	tsconfig.json
--target	Entry points where compiled files are placed for modification	If not specified inherited from tsconfig.json compilerOptions.outDir
--dirnameVar	Replace __dirname usages with import.meta	true
--filenameVar	Replace __filename var references import.meta	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

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
  out?: string,
  target?: string | string[]
  tsconfig?: string | string[]
  dirnameVar: boolean
  filenameVar: boolean
  ext: boolean | string
  unlink?: boolean
}

Alternatives

• https://github.com/mothepro/tsc-esm
• https://github.com/digital-loukoum/tsc-esm

License

MIT

Changelog

2.5.0 (2021-08-18)

Bug Fixes

• handle directories with file-like names (8c60d3f)

Features

• introduce unlink CLI flag (af31516)