rollup.plugin.size.js

import byteSize from 'byte-size';

const manifest = [];

process.on('beforeExit', () => {
  console.table(manifest);
});

export default () => ({
  name: 'Size',
  generateBundle(_, bundles) {
    Object.entries(bundles).forEach(([key, bundle]) => {
      if (bundle.code) {
        manifest.push([key, '' + byteSize(bundle.code.length, {
          units: 'iec',
        })]);
      } else if (bundle.source) {
        manifest.push([key, '' + byteSize(bundle.source.length, {
          units: 'iec',
        })]);
      }
    });
  },
});