RequireJS ESM Converter

Converts source RequireJS modules from AMD to ESM format.

If you enabled usage of ESM modules in your RequireJS project (using requirejs-babel7, requirejs-esm or requirejs-esm-preprocessor, for example), you might want to convert all your code base to the ESM format to follow the same consistent coding standard and use the same set of tools to build, test and analyse your sources.

Synopsis

Convert all JavaScript sources in the project's subdirectories:

❯ requirejs-to-esm '*/**/*.js' '!node_modules'

lib/impl/analyse.js: converted
lib/impl/convert.js: converted
lib/index.js: multiple statements
test/index.js: converted

The file lib/index.js wasn't an AMD module. (It didn't contain a single define or require statement.) It will need an inspection and manual conversion.

Installation

This module can be installed globally using NPM, PNPM or Yarn. Make sure, that you use Node.js version 14 or newer.

npm i -g requirejs-esm-converter
pnpm i -g requirejs-esm-converter
yarn add --global requirejs-esm-converter

Command Line

requirejs-to-esm [option...] [<pattern> ...]

You can use BASH patterns for including and excluding files (only files). Patterns are case-sensitive and have to use slashes as directory separators. A pattern to exclude from processing starts with "!".

Options

-d|--[no-]dry-run  only log results, no writing to files
-p|--[no-]print    write to stdout instead of overwriting files
-V|--version       print version number
-h|--help          print usage instructions

Files will overwritten with the converted output, if they are recognised as AMD modules and if the dry-run mode is not enabled.

Examples

requirejs-to-esm '**/*.js' '!node_modules'
requirejs-to-esm -d "lib/*.js"
echo "define({})" | requirejs-to-esm"

API

convert(source: string): { code: string, warnings: string[] }

The function convert converts the source in AMD to code in ESM, optionally returning warnings. If the conversion is impossible because the input is not an AMD module, it will throw ConvertError. If the source file cannot be parsed, it will throw SyntaxError.

import { convert } from 'requirejs-to-esm'

const input =`define(["test"], function (test) {
  "use strict";
  console.log('imported:', test);
  return 42; // ultimate answer
});`
const { code } = convert(input)
console.log(code)

// Result:
//
// import test from "test";
//
// console.log('imported:', test);
// export default 42; // ultimate answer

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Lint and test your code.

License

Copyright (c) 2022-2024 Ferdinand Prantl

Licensed under the MIT license.