rollup.main.config.js

import babel from '@rollup/plugin-babel';
import nodeResolve from '@rollup/plugin-node-resolve';
import replace from '@rollup/plugin-replace';
import Visualizer from 'rollup-plugin-visualizer';

const entries = {
  min: 'lib/index.js',
  umd: 'lib/index.js',
};

const dests = {
  min: 'dist/diffhtml.min.js',
  umd: 'dist/diffhtml.js',
};

const { NODE_ENV = 'umd' } = process.env;

export default {
  input: entries[NODE_ENV],
  context: 'this',
  output: [{
    file: dests[NODE_ENV],
    format: 'umd',
    exports: 'named',
    name: 'diff',
    sourcemap: false,
  }],
  plugins: [
    NODE_ENV === 'min' && replace({
      'internalProcess.env.NODE_ENV': JSON.stringify('production'),
      preventAssignment: true,
    }),
    babel({
      comments: false,
      babelHelpers: 'runtime',
      skipPreflightCheck: true,
    }),
    nodeResolve({ mainFields: ['module'] }),
    NODE_ENV === 'min' && Visualizer.default({ filename: './dist/main-build-size.html' }),
  ],
};