Rollup configuration for size comparison

lwc.rollup.config.js

// Run via `yarn rollup -c rollup.config.js` at the root of the lwc repo

import path from 'path';
import replace from '@rollup/plugin-replace';
import { terser } from 'rollup-plugin-terser';

const input = path.resolve(__dirname, 'packages/lwc/dist/engine/esm/es2017/engine.js');
const replaceConfig = {
    'process.env.NODE_ENV': JSON.stringify('production'),
};
const terserConfig = {
    output: {
        comments: false,
    }
};

export default [
    {
        input,
        output: {
            file: 'dist/original.js',
        },
    },
    {
        input,
        plugins: [replace(replaceConfig)],
        output: {
            file: 'dist/prod.js',
        },
    },
    {
        input,
        plugins: [terser(terserConfig)],
        output: {
            file: 'dist/minified.js',
        },
    },
    {
        input,
        plugins: [replace(replaceConfig), terser(terserConfig)],
        output: {
            file: 'dist/prod-minified.js',
        },
    },
];

size.md

Bundle name	Parsing size (without gzip, KB)	Download size (with gzip, in KB)
Original	193	42
Minified (terser)	64	19
Production (replace process.env.NODE_ENV)	143	34
Minified + Production (terser + replace process.env.NODE_ENV)	38	13