[Webpack] Create Separate webpack Configs for Development and Production with webpack-merge

The development and production modes in webpack optimize the output in different ways. In development mode, the focus is on faster builds and a better developer experience. In production mode, the focus is on highly optimized bundles, leading to a better user experience. The good news is, we can have both. In this lesson, we'll separate our webpackconfig into two configurations and update our scripts to run the right config for our needs.

Install:

npm i -D webpack-merge

Create a webpack.config.base.jf:

const path = require('path')
const HtmlWebpackPlugin = require('html-webpack-plugin')

module.exports = {
  entry: './src/index.js',
  output: {
    path: path.join(__dirname, 'dist'),
    filename: 'app.bundle.js'
  },
  module: {
    rules: [
      {
        test: /.js$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        options: {
          presets: ['@babel/preset-env', '@babel/preset-react']
        }
      }
    ]
  },
  plugins: [new HtmlWebpackPlugin({
    template: './src/index.html'
  })]
}

webpack.config.dev.js:

const merge = require('webpack-merge')
const baseConfig = require('./webpack.config.base')

module.exports = merge(baseConfig, {
  mode: 'development'
})

webpack.config.prod.js:

const merge = require('webpack-merge')
const baseConfig = require('./webpack.config.base')

module.exports = merge(baseConfig, {
  mode: 'production'
})

Update scripts to adopt changes:

"scripts": {
    "build": "webpack --config webpack.config.prod.js",
    "dev": "webpack --watch --config webpack.config.dev.js",
    "test": "echo "Error: no test specified" && exit 1"
  }