js-main

Checks if the current module is the main executed module.

• Supports both ES and CJS modules.
• Works with Bun, Deno and Node.js.
• Includes TypeScript types.
• Zero dependencies.
• As efficient as possible depending on the completeness of import.meta.
• Tiny size - 503 B original, 295 B minified, 216 B gzipped, 193 B brotlied.

Node.js version 14 and newer is supported.

Synopsis

ES

1import { isMain } from 'js-main'
2
3if (isMain(import.meta)) {
4  // this module has been executed
5}

CJS

1const { isMain } = require('js-main')
2
3if (isMain(module)) {
4  // this module has been executed
5}

Installation

You can install this package using your favourite package manager:

1npm i -D js-main
2yarn add -D js-main
3pnpm i -D js-main
4bun i -D js-main

API

This package exports one named function:

1function isMain(import.meta | module): boolean

It expects the expression import.meta as the first parameter in an ES module and module in a CJS module. It returns a boolean, which will be true if the current module is the main executed module.

Importing

ES or CJS export will be chosen according to the type from package.json of the importing package. The ES export type can be enforced by the path suffix /es:

1import { isMain } from 'js-main'
2import { isMain } from 'js-main/es'

The CJS export type can be enforced by the path suffix /cjs:

1const { isMain } = require('js-main')
2const { isMain } = require('js-main/cjs')

About CJS

If you use only CJS modules, you can use the following code without depending on this or any other package:

1if (require.main === module) {
2  // this module has been executed
3}

Contributing

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

git clone https://github.com/prantlf/js-main.git
bun i --frozen-lockfile
bun run lint
bun run test

License

Copyright (c) 2024 Ferdinand Prantl

Licensed under the MIT license.