sass-site/rollup.config.js

import { babel } from '@rollup/plugin-babel';
import commonjs from '@rollup/plugin-commonjs';
import inject from '@rollup/plugin-inject';
import { nodeResolve } from '@rollup/plugin-node-resolve';
import terser from '@rollup/plugin-terser';

const prod = process.env.BABEL_ENV === 'production';

const plugins = [
  nodeResolve({ browser: true }),
  commonjs(),
  inject({
    $: 'jquery',
    jQuery: 'jquery',
  }),
  babel({ babelHelpers: 'bundled' }),
];

if (prod) {
  plugins.push(terser());
}

export default {
  input: 'source/assets/js/sass.js',
  output: {
    file: 'source/assets/dist/js/sass.js',
    format: 'iife',
    sourcemap: !prod,
  },
  plugins,
};