rollup.config.js

import autoprefixer from "autoprefixer";
import commonjs from "rollup-plugin-commonjs";
import nodeResolve from "rollup-plugin-node-resolve";
import postcss from "rollup-plugin-postcss";

// code for using uglify-es modified from https://github.com/TrySound/rollup-plugin-uglify
const minify = require("uglify-es").minify; // eslint-disable-line

function uglify(userOptions) {
  const options = Object.assign(
    {
      sourceMap: true
    },
    userOptions
  );

  return {
    name: "uglify",
    transformBundle(code) {
      const result = minify(code, options);
      if (result.error) {
        throw result.error;
      }
      return result;
    }
  };
}

export default {
  input: "src/main.js",
  output: {
    file: "dist/bundle.js",
    format: "iife", // change to 'iife' for production, 'es' to test
    sourcemap: true,
    banner: "/* https://www.elsewebdevelopment.com/ */"
  },
  plugins: [
    nodeResolve({
      jsnext: true, // Default: false
      main: true,
      browser: true // Default: false
    }),
    commonjs({
      // if false then skip sourceMap generation for CommonJS modules
      sourceMap: true // Default: true
    }),
    postcss({
      plugins: [autoprefixer()],
      sourceMap: true,
      extract: true,
      minimize: true
    }),
    uglify()
  ]
};