babel.config.js

'use strict';

const {name, version, engines} = require('./package.json');

const node = engines.node
	.split(/[^\d.]+/)
	.filter(s => s.length)
	.map(s => [...s.split('.').map(s => +s || 0), 0, 0].slice(0, 3))
	.sort((a, b) => a[2] - b[2])
	.sort((a, b) => a[1] - b[1])
	.sort((a, b) => a[0] - b[0])[0]
	.join('.');

module.exports = api => {
	const env = api.env();
	api.cache(() => env);
	const modules = env === 'esm' ? false : 'commonjs';
	const ext = modules ? '.js' : '.mjs';
	const presets = [];
	const plugins = [];
	presets.push([
		'@babel/preset-env',
		{
			modules,
			exclude: ['proposal-dynamic-import'],
			targets: {
				node
			}
		}
	]);
	presets.push(['@babel/preset-typescript']);
	if (modules === 'commonjs') {
		plugins.push([
			'@babel/plugin-transform-modules-commonjs',
			{
				importInterop: 'node'
			}
		]);
	}
	plugins.push([
		'esm-resolver',
		{
			source: {
				extensions: [
					[['.js', '.mjs', '.jsx', '.mjsx', '.ts', '.tsx'], ext]
				]
			}
		}
	]);
	plugins.push([
		'search-and-replace',
		{
			rules: [
				{
					search: '#{NAME}',
					replace: name
				},
				{
					search: '#{VERSION}',
					replace: version
				}
			]
		}
	]);
	return {
		presets,
		plugins
	};
};