rollup.config.js

import fs from 'fs';
import alias from 'rollup-plugin-alias';
import memory from 'rollup-plugin-memory';
import babel from 'rollup-plugin-babel';
import nodeResolve from 'rollup-plugin-node-resolve';
import commonjs from 'rollup-plugin-commonjs';
import replace from 'rollup-plugin-replace';
import es3 from 'rollup-plugin-es3';

const babelRc = JSON.parse(fs.readFileSync('.babelrc'));
let pkg = JSON.parse(fs.readFileSync('./package.json'));

let external = Object.keys(pkg.peerDependencies || {}).concat(Object.keys(pkg.dependencies || {}));

let format = process.env.FORMAT==='es' ? 'es' : 'umd';

babelRc.plugins.push('external-helpers');

export default {
	entry: 'src/index.js',
	sourceMap: true,
	moduleName: pkg.amdName,
	exports: format==='es' ? null : 'default',
	dest: format==='es' ? pkg.module : pkg.main,
	format,
	external,
	useStrict: false,
	globals: {
			'preact': 'preact',
			'redux': 'Redux'
	},
	plugins: [
		format==='umd' && memory({
			path: 'src/index.js',
			contents: "export { default } from './index';"
		}),
		{
			// This insane thing transforms Lodash CommonJS modules to ESModules. Doing so shaves 500b (20%) off the library size.
			load: function(id) {
				if (id.match(/\blodash\b/)) {
					return fs.readFileSync(id, 'utf8')
						.replace(/\b(?:var\s+)?([\w$]+)\s*=\s*require\((['"])(.*?)\2\)\s*[,;]/g, 'import $1 from $2$3$2;')
						.replace(/\bmodule\.exports\s*=\s*/, 'export default ');
				}
			}
		},
		alias({
			'react-redux': 'node_modules/react-redux/src/index.js',
			'react': __dirname+'/src/compat.js',
			'invariant': __dirname+'/src/empty.js',
			'prop-types': __dirname+'/src/prop-types.js'
		}),
		babel({
			babelrc: false,
			presets: [
				['es2015', {
					loose: true,
					modules: false
				}]
			].concat(babelRc.presets.slice(1)),
			plugins: babelRc.plugins
		}),
		nodeResolve({
			jsnext: true,
			main: true,
			preferBuiltins: false
		}),
		commonjs({
			include: ['node_modules/**'],
			exclude: [ 'node_modules/react-redux/**']
		}),
		replace({ 'process.env.NODE_ENV': JSON.stringify('production') }),
		es3()
	].filter(Boolean)
};