Learn Webpack Basics in 2 days

Oct 5, 2017 6 mins read 5ce52262a
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Introduction

Learn from https://webpack.js.org/guides/getting-started/

Clone my repo to follow commit hash by section : https://github.com/khanhicetea/learn-n-earn

Day 1 , <51ede10>

webpack.config.js

const path = require('path');

module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

Bash

$ ./node_modules/.bin/webpack --config webpack.config.js

Learned

  • entry : start point to dive in dependency graph.
  • output : output after pack the web modules
    • filename : bundle filename
    • path : dist path

Day 2

Import assets , <07591ed>

  • CSS file : use style-loader and css-loader
  • Image file : use file-loader
  • WebFont file : use file-loader
  • Data file use json-loader, xml-loader or csv-loader
module: {
    rules: [
      {
        test: /\.css$/,
        use: [
          'style-loader',
          'css-loader'
        ],
      },
      {
        test: /\.(png|jpe?g|gif|webp)$/,
        use: [
          'file-loader'
        ],
      },
      {
        test: /\.(woff|woff2|eot|ttf|otf)$/,
        use: [
          'file-loader'
        ]
      }
    ]
  }

Dynamic output and entry ,

entry config can be a dictionary where key is entry name and value is entry file path output.filename could use [name] in syntax to generate dynamic output filename

module.exports = {
  entry: {
    app: './src/index.js',
    print: './src/print.js'
  },
  output: {
    filename: '[name].bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

HtmlWebpackPlugin

HtmlWebpackPlugin by default will generate its own index.html file, even though we already have one in the dist/ folder

npm install html-webpack-plugin --save-dev

Cleaning /dist folder

To clean up dist folder automatically !

npm install clean-webpack-plugin --save-dev
const CleanWebpackPlugin = require('clean-webpack-plugin');

...
plugins: [
  new HtmlWebpackPlugin(['dist']),
],

Development

Source map , <4eea0dc>

To enable source map for js and css file, use inline-source-map option in devtool config

...
devtool: 'inline-source-map',
plugins: [
  ...
],

ONLY USE THIS OPTION FOR DEVELOPMENT MODE

Development server (watch file changes) ,

  • watch mode : add option --watch to webpack cli run command
  • webpack-dev-server : use npm package webpack-dev-server and add devServer: { contentBase: './dist' } to webpack config, when start a dev server use another command instead webpack-dev-server --open
  • express webpack-dev-middleware : use webpack-dev-middleware as Express middleware

Ready for production , <1ddcee3>

Tree shaking

Tree shaking is a term commonly used in the JavaScript context for dead-code elimination. It relies on the static structure of ES2015 module syntax, i.e. import and export.

$ npm install --save-dev uglifyjs-webpack-plugin
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');

...
plugins: [
    ...
    new UglifyJSPlugin(),
]

ONLY USE IN PRODUCTION WEBPACK CONFIG

Setup multi environments ,

$ npm install --save-dev webpack-merge

webpack.common.js

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

module.exports = {
  entry: {
    app: './src/index.js',
    print: './src/print.js'
  },
  plugins: [
    new HtmlWebpackPlugin(['dist']),
    new HtmlWebpackPlugin({
      title: 'Output Management'
    }),
  ],
  output: {
    filename: '[name].bundle.js',
    path: path.resolve(__dirname, 'dist')
  }
};

webpack.dev.js

const merge = require('webpack-merge');
const common = require('./webpack.common.js');

module.exports = merge(common, {
    devtool: 'inline-source-map',
    devServer: {
      contentBase: './dist'
    }
});

webpack.prod.js

const merge = require('webpack-merge');
const common = require('./webpack.common.js');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');

module.exports = merge(common, {
    plugins: [
        new UglifyJSPlugin()
    ]
});

package.json

  "scripts": {
    "build": "webpack --config webpack.prod.js",
    "dev": "webpack-dev-server --open --config webpack.dev.js"
  }

Run command

  • npm run dev : running dev server with hot reload
  • npm run build : build production dist

Specify the Environment

Many libraries will key off the process.env.NODE_ENV variable to determine what should be included in the library. We can use webpack’s built in DefinePlugin to define this variable for all our dependencies

webpack.prod.js

const webpack = require('webpack');
const merge = require('webpack-merge');
const common = require('./webpack.common.js');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');

module.exports = merge(common, {
  plugins: [
      new UglifyJSPlugin(),
      new webpack.DefinePlugin({
        'process.env': {
          'NODE_ENV': JSON.stringify('production')
        }
      })
  ]
});
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