Webpack

https://webpack.js.org/

https://slides.com/tylergraf/webpack

Warning

Webpack's documentation, although extensive, is only helpful if you speak webpack already.

https://bit.ly/2S09TS7

https://github.com/tylergraf/level-up-webpack​

or

What the cr*p is it?

It's a module bundler.

What's a module bundler?

add.js

index.js

subtract.js

bundle.js

import add from './add.js';
import subtract from './subtract.js';

console.log(`Add: ${add(4,5)}`);
console.log(`Subtract: ${subtract(9,5)}`);

const add = (a, b) => {
  return a + b;
}

export default add;

const subtract = (a, b) => {
  return a - b;
}

export default subtract;

index.js

add.js

subtract.js

const add = (a, b) => {
  return a + b;
}

const subtract = (a, b) => {
  return a - b;
}

console.log(`Add: ${add(4,5)}`);
console.log(`Subtract: ${subtract(9,5)}`);

bundle.js

Well, kinda

/******/ (function(modules) { // webpackBootstrap
/******/ 	// The module cache
/******/ 	var installedModules = {};
/******/
/******/ 	// The require function
/******/ 	function __webpack_require__(moduleId) {
/******/
/******/ 		// Check if module is in cache
/******/ 		if(installedModules[moduleId]) {
/******/ 			return installedModules[moduleId].exports;
/******/ 		}
/******/ 		// Create a new module (and put it into the cache)
/******/ 		var module = installedModules[moduleId] = {
/******/ 			i: moduleId,
/******/ 			l: false,
/******/ 			exports: {}
/******/ 		};
/******/
/******/ 		// Execute the module function
/******/ 		modules[moduleId].call(module.exports, module, module.exports, __webpack_require__);
/******/
/******/ 		// Flag the module as loaded
/******/ 		module.l = true;
/******/
/******/ 		// Return the exports of the module
/******/ 		return module.exports;
/******/ 	}
/******/
/******/
/******/ 	// expose the modules object (__webpack_modules__)
/******/ 	__webpack_require__.m = modules;
/******/
/******/ 	// expose the module cache
/******/ 	__webpack_require__.c = installedModules;
/******/
/******/ 	// define getter function for harmony exports
/******/ 	__webpack_require__.d = function(exports, name, getter) {
/******/ 		if(!__webpack_require__.o(exports, name)) {
/******/ 			Object.defineProperty(exports, name, { enumerable: true, get: getter });
/******/ 		}
/******/ 	};
/******/
/******/ 	// define __esModule on exports
/******/ 	__webpack_require__.r = function(exports) {
/******/ 		if(typeof Symbol !== 'undefined' && Symbol.toStringTag) {
/******/ 			Object.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });
/******/ 		}
/******/ 		Object.defineProperty(exports, '__esModule', { value: true });
/******/ 	};
/******/
/******/ 	// create a fake namespace object
/******/ 	// mode & 1: value is a module id, require it
/******/ 	// mode & 2: merge all properties of value into the ns
/******/ 	// mode & 4: return value when already ns object
/******/ 	// mode & 8|1: behave like require
/******/ 	__webpack_require__.t = function(value, mode) {
/******/ 		if(mode & 1) value = __webpack_require__(value);
/******/ 		if(mode & 8) return value;
/******/ 		if((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;
/******/ 		var ns = Object.create(null);
/******/ 		__webpack_require__.r(ns);
/******/ 		Object.defineProperty(ns, 'default', { enumerable: true, value: value });
/******/ 		if(mode & 2 && typeof value != 'string') for(var key in value) __webpack_require__.d(ns, key, function(key) { return value[key]; }.bind(null, key));
/******/ 		return ns;
/******/ 	};
/******/
/******/ 	// getDefaultExport function for compatibility with non-harmony modules
/******/ 	__webpack_require__.n = function(module) {
/******/ 		var getter = module && module.__esModule ?
/******/ 			function getDefault() { return module['default']; } :
/******/ 			function getModuleExports() { return module; };
/******/ 		__webpack_require__.d(getter, 'a', getter);
/******/ 		return getter;
/******/ 	};
/******/
/******/ 	// Object.prototype.hasOwnProperty.call
/******/ 	__webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };
/******/
/******/ 	// __webpack_public_path__
/******/ 	__webpack_require__.p = "";
/******/
/******/
/******/ 	// Load entry module and return exports
/******/ 	return __webpack_require__(__webpack_require__.s = "./src/index.js");
/******/ })
/************************************************************************/
/******/ ({

/***/ "./src/add.js":
/*!********************!*\
  !*** ./src/add.js ***!
  \********************/
/*! exports provided: default */
/***/ (function(module, __webpack_exports__, __webpack_require__) {

"use strict";
eval("__webpack_require__.r(__webpack_exports__);\nconst add = (a, b) => {\n  return a + b;\n}\n\n/* harmony default export */ __webpack_exports__[\"default\"] = (add);\n\n\n//# sourceURL=webpack:///./src/add.js?");

/***/ }),

/***/ "./src/index.js":
/*!**********************!*\
  !*** ./src/index.js ***!
  \**********************/
/*! no exports provided */
/***/ (function(module, __webpack_exports__, __webpack_require__) {

"use strict";
eval("__webpack_require__.r(__webpack_exports__);\n/* harmony import */ var _add_js__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(/*! ./add.js */ \"./src/add.js\");\n/* harmony import */ var _subtract_js__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(/*! ./subtract.js */ \"./src/subtract.js\");\n\n\n\nconsole.log(`Add: ${Object(_add_js__WEBPACK_IMPORTED_MODULE_0__[\"default\"])(4,5)}`);\nconsole.log(`Subtract: ${Object(_subtract_js__WEBPACK_IMPORTED_MODULE_1__[\"default\"])(9,5)}`);\n\n\n//# sourceURL=webpack:///./src/index.js?");

/***/ }),

/***/ "./src/subtract.js":
/*!*************************!*\
  !*** ./src/subtract.js ***!
  \*************************/
/*! exports provided: default */
/***/ (function(module, __webpack_exports__, __webpack_require__) {

"use strict";
eval("__webpack_require__.r(__webpack_exports__);\nconst subtract = (a, b) => {\n  return a - b;\n}\n\n/* harmony default export */ __webpack_exports__[\"default\"] = (subtract);\n\n\n//# sourceURL=webpack:///./src/subtract.js?");

/***/ })

/******/ });

bundle.js

Try it out

1-basic

Basic Webpack Config

webpack.config.js

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

Entry file

Output

Module Types

ES Modules

const add = (a, b) => a + b;

export default add;

add.js

import add from './add.js'

add(2,2); //5

index.js

define((a,b) => {
  return a + b;
});

add.js

define(['./add'], (add) => {
  add(2,2); //5
});

index.js

module.exports = (a,b) => {
  return a + b;
}

add.js

const add = require('./add.js');

add(2,2); //5

index.js

AMD

(dojo, require.js)

Common JS

(node)

Export

Import

UMD

Universal Module Definition

CJS?

(function (root, factory) {
  if(typeof exports === 'object' && typeof module === 'object')
    module.exports = factory();
  else if(typeof define === 'function' && define.amd)
    define([], factory);
  else {
    var a = factory();
    for(var i in a) (typeof exports === 'object' ? exports : root)[i] = a[i];
  }
})(window, function() {
// my code
});

AMD?

K, fine global

Input

  • AMD
  • UMD (CommonJS)
  • CommonJS
  • SystemJS
  • browserify
  • requireJs
  • ES Module

Webpack uses node (CommonJS) under the hood

import thing from 'thing.js'
const thing = require('thing.js')
export default thing;
module.exports = thing;

Output

  • jsonp (default)
  • CommonJS
  • AMD
  • UMD
  • global (IIFE)
  • ES Module

Pull in node modules

import { sortBy } from 'lodash'; // automatically resolves to node_modules

const users = [
  { 'user': 'fred',   'age': 48 },
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 },
  { 'user': 'barney', 'age': 34 }
];

console.log(sortBy(users, ['user', 'age']));

$ npm i lodash

ES Module Syntax

Try it out

2-node-module

Webpack supports HTML

import personHTML from './person.html';
import './style.css';

let el = document.createElement('div');
el.innerHTML = personHTML;

document.body.appendChild(el);

index.js

<div class="person">
  <img src="./tyler.jpg" class="photo">
  <p class="name">Tyler Graf</p>
</div>

person.html

HTML is Easy

import personHTML from './person.html';
import styles from './style.css';
.person {
  display: flex;
  align-items: center;
}
.photo {
  height: 80px;
  width: 80px;
}
.name {
  margin-left: 10px;
  font-size: 30px;
}

style.css

module.exports = {
  entry: './src/index.js',
  mode: 'development',
  output: {
    path: __dirname + '/dist',
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.(html)$/,
        use: {
          loader: 'html-loader'
        }
      },
      {
        test: /\.css$/,
        use: [
          { loader: "style-loader" },
          { loader: "css-loader" }
        ]
      }
    ]
  }
}

Loaders

Everything in webpack is a module

Loaders just transform things into javascript modules*

*kinda

html-loader

<div>
  <span>Tyler Graf</span>
</div>
module.exports = '<div><span>Tyler Graf</span></div>'

HTML

JavaScript

import html from './person.html';

let el = document.createElement('div');
el.innerHTML = html;

import html as a string

module.exports = '<div><span>Tyler Graf</span></div>'

person.html

html-loader

style-loader

.name {
  font-size: 30px;
}
module.exports = appendToHead('<style>.name {font-size: 30px;}</style>')

CSS

JavaScript

import 'style.css';

Webpack will automatically append this to the <head>

style-loader

module.exports = appendToHead('<style>.name {font-size: 30px;}</style>')

style.css

Try it out

3-html

Loader Config

module.exports = {
  entry: './src/index.js',
  output: {
    path: __dirname + '/dist',
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.(html)$/,
        use: {
          loader: 'html-loader'
        }
      }
    ]
  }
}

Entry file

Output

Loaders

which files go through this loader

name of the loader

html-loader

<div class="person">
  <img src="./tyler.jpg" class="photo">
  <p class="name">Tyler Graf</p>
</div>

module.exports = `
<div class="person">
  <img src="${require('./tyler.jpg')}" class="photo">
  <p class="name">Tyler Graf</p>
</div>
`;

external file

external file

file-loader

module.exports = {
  entry: './src/index.js',
  output: {
    path: __dirname + '/dist',
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.(png|jpg|gif)$/i,
        use: [
          {
            loader: 'file-loader',
            options: {
              name(file) {
                return '../[path][name].[ext]';
              }
            }
          }
        ]
      }
    ]
  }
}

Options

multiple filename endings

Try it out

3-html

Why the cr*p?

Moto G4 3G (1.6Mbps/768Kbps)

Tree Landscape Pedigree

Wasatch Desktop Cable (5/1Mbps)

Tree Landscape Pedigree

webpage test comparison

Tree Pedigree

429KB

375KB

12%

10.2s

8.5s

16%

Moto G4 from Virginia - 3G (1.6Kbps/768Kbps)

3.2s

2.5s

32%

Wasatch Front Desktop - Cable (5/1Mbps)

Tree Person Waterfalls

265 Reqs

87 Reqs

9.5s

17s

775KB

354KB

54%

67%

44%

Philippines Desktop - 3G (1.6Mbps/768Kbs)

Bundling is still necessary for top performance

Code Splitting

Only load the code you need, when you need it.

el.addEventListener('click', e => {

  //dynamic import after a click
  import('./add.js').then(({default:add})=>{

    //I now have access to the new module
    add(2,2);

  });
});

renamed and destructured

add.js won't load until this import is called

Try it out

4-code-splitting

Polymer 2

polymer-webpack-loader

import './my-app.html';
module.exports = {
  ...
  module: {
    rules: [
      {
        test: /\.(html)$/,
        use: {
          loader: 'polymer-webpack-loader'
        }
      }
    ]
  }
}

index.js

webpack.config.js

<my-app></my-app>
    
<script src="./dist/bundle.js"></script>

index.html

Try it out

5-polymer-2

Loaders

more in depth

Loaders take a string and return a string 

module.exports = (source) => {

  source = source.replace('stuff','things');

  return source;
};

string

string

do a transformation

thing-replace-loader.js

items.map(item=>{

  return item.replace('stuff','thing');

});

Remind's me of a map function

add.js

index.js

subtract.js

bundle.js

replace-loader

once for each file

{
  ...
  module: {
    rules: [
      {
        test: /\.html$/,
        use: [
          { loader: 'polymer-webpack-loader' },
          { loader: 'webpack-lazy-group-loader' }
        ]
      }
    ]
  }
}

Loaders run in reverse order. Weird.

Hey webpack,

Whenever you find a filename that ends in .html, run it through these loaders.

Thanks.

First

Second

resolved to node_modules. Weird.

lazy-imports

(code splitting)

<link rel="lazy-import" group="profile" href="./my-profile.html">

...

loadProfile() {

  this.importLazyGroup('profile').then();

}

Don't load ./my-profile.html until loadProfile is called.

webpack-lazy-group-loader

module.exports = (source) => {
  // if no `importLazyGroup` just return source.
  if(!source.includes('importLazyGroup')) return source;

  var doc = parse5.parseFragment(source);

  var scriptEls = dom5.queryAll(doc, pred.hasTagName('script'));

  // find all lazy-import groups
  const lazyGroups = parseLazyGroups(doc);

  scriptEls.forEach(scriptEl=>{
    source = replaceLazyImports(doc, scriptEl, lazyGroups);
  });

  return source;
};

https://github.com/fs-webdev/webpack-lazy-group-loader

<link rel="lazy-import" group="profile" href="./my-profile.html">

...

loadProfile() {

  this.importLazyGroup('profile').then();

}
loadProfile() {

  import('./my-profile.html')

}

webpack-lazy-group-loader

Plugins

https://webpack.js.org/plugins/

add.js

index.js

subtract.js

bundle.js

replace-loader

once for each file

UglifyPlugin

Only one time

module.exports = {
  ...
  plugins: [
    new UglifyJsPlugin({
      sourceMap: true,
      uglifyOptions: {
        mangle: {
          safari10: true
        }
      }
    })
  ]
}

Plugin in config

Try it out

6-plugin

HMR

hot module replacement

https://webpack.js.org/guides/hot-module-replacement/

Good luck with these docs

Try it out

7-hmr

https://color--game.herokuapp.com

On your touch device

2 dashes

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