ESM Config

Transform ES module configs to cjs using rollup.

Why?

Since ES6 import and export are standard, yet there is still ~~no support~~ only experimental support in NodeJS.

Most of the time that is not a problem, since projects have a build step transforming (webpack/rollup/babel) the syntax. So people expect import/export to just work.

This module allows you to use ES modules syntax to write your configuration. Build a project or framework that allows more advanced configuration than toml, yaml or json would. Like rollup.config.js, webpack.config.js, or postcss.config.js. (Only rollup allows import/export out of the box).

Usage

Within your project let esm-config import your configuration file.

const esmConfig = require("esm-config")

// /example/config.js may contain import/export syntax
const config = esmConfig("/example/config.js")

// you can provide a default configuration
// it is used, if the config file does not exist
// it is passed, if the config file exports a function
const defaultConfiguration = {
	name: "defaultName"
}
const config = esmConfig("/example/config.js", defaultConfiguration)

The configuration can then be written as either ESM or CJS module.

// example ESM config
export default {
	name: "hello world"
}

// example exporting a function
// is passed the default configuration
export default function(defaultConfiguration) {
	const { name } = defaultConfiguration
	return {
		name,
		otherConfig: false
	}
}

// example CJS config
// this would work in nodejs without esm-config
module.exports = {
	name: "hello world"
}

Background

This uses a modified version of rollups internal loadConfigFile function.

Rollup configs can be written using ES modules syntax, because rollup transforms them to CJS before using them.

License

MIT