Unbundling the JavaScript module bundler - DevIT

The landscape of module bundlers has evolved significantly since the days you would manually copy-paste your libraries to create a package for your frontend app. Like many parts of the JS world, the evolution has happened somewhat haphazardly, and the pace of change can feel overwhelming. Has Webpack ever felt like magic to you? How well do you understand what’s really going on under the hood? In this talk, I will uncover the history of JS module bundlers and illustrate how they actually work. Once we have the basics down, I will dive deeper into some of the more advanced topics, such as bundle cache boost and resolving cycling dependencies. At the end of this session, you will have a much more profound understanding of what’s going on behind the scenes.

Transcript

1. Unbundling the JavaScript Unbundling the JavaScript module bundler module bundler Luciano Mammino - Luciano Mammino - @loige @loige 10/06/2019 loige.link/bundle-devit 1
2. Webpack == PAIN!? Webpack == PAIN!? twitter.com/search?q=webpack%20pain @loige 2
3. @loige 3
4. @loige 4
5. @loige 5
6. @loige ❤ 6
7. @loige 7
8. @loige 8
9. @loige 9
10. It's not Webpack! It's not Webpack! Module bundling is actually complicated! Module bundling is actually complicated! @loige 10
12. Hello, I am Luciano! Hello, I am Luciano! 11
13. Hello, I am Luciano! Hello, I am Luciano! 11
14. Hello, I am Luciano! Hello, I am Luciano! 11
15. Hello, I am Luciano! Hello, I am Luciano! 11
16. Hello, I am Luciano! Hello, I am Luciano! Cloud Architect 11
17. Hello, I am Luciano! Hello, I am Luciano! Cloud Architect Blog: Twitter: GitHub: loige.co @loige @lmammino 11
18. Hello, I am Luciano! Hello, I am Luciano! Cloud Architect Blog: Twitter: GitHub: loige.co @loige @lmammino 11
19. loige.link/bundle-devit 12
20. 1. Why we need modules 2. JavaScript module systems 3. How a module bundler works 4. Webpack in 2 minutes! 5. Advanced module bundling Agenda Agenda @loige 13
21. https://poo.loige.co @loige 14
22. App features App features @loige 15
23. Dynamic DOM manipulation React, Angular, Vue are so... overrated! @loige 16
24. Dynamic Favicon favico.js @loige 17
25. Custom animated tooltips tippy.js @loige 18
26. Confetti rainfall dom-confetti @loige 19
27. Persist state through Local Storage + UUIDs + store2 uuidjs @loige 20
28. @loige 21
29. @loige 21
30. 7 Requests only for the JS code! @loige 21
31. Current scenario Current scenario zepto@1.2.0/dist/zepto.min.js uuidjs@4.0.3/dist/uuid.core.js store2@2.7.0/dist/store2.min.js tippy.js@2.2.3/dist/tippy.all.min.js confetti@0.0.10/lib/main.js favico.js@0.3.10/favico­0.3.10.min.js @loige 22
32. Ideal scenario Ideal scenario zepto@1.2.0/dist/zepto.min.js uuidjs@4.0.3/dist/uuid.core.js store2@2.7.0/dist/store2.min.js tippy.js@2.2.3/dist/tippy.all.min.js confetti@0.0.10/lib/main.js favico.js@0.3.10/favico­0.3.10.min.js vendors.js + + + + + = @loige 23
33. How to do this? How to do this? @loige 24
34. ./buildVendors.sh > vendors.js buildVendors.sh $ @loige 25
35. npx lumpy build $ github.com/lmammino/lumpy @loige 26 . 1
36. # lumpy.txt https://unpkg.com/zepto@1.2.0/dist/zepto.min.js https://unpkg.com/uuidjs@4.0.3/dist/uuid.core.js https://unpkg.com/store2@2.7.0/dist/store2.min.js https://unpkg.com/tippy.js@2.2.3/dist/tippy.all.min.js https://unpkg.com/confetti­js@0.0.11/dist/index.min.js https://unpkg.com/dom­confetti@0.0.10/lib/main.js https://unpkg.com/favico.js@0.3.10/favico­0.3.10.min.js Lumpy allows you to define all the vendors in a text file @loige 26 . 2
37. lumpy build $ 1. Downloads the files from lumpy.txt (and caches them) 2. Concatenates the content of the files 3. Minifies the resulting source code (using ) 4. Saves the resulting content in vendors.js babel-minify @loige 26 . 3
38. 7 requests 2 requests @loige 27
39. 7 requests 2 requests @loige Even better if you "minify" these! 27
40. Concatenation Concatenation + + Minification Minification @loige 28
41. This is good... This is good... @loige 29
42. This is good... This is good... @loige 29
43. This is good... This is good... ... in 2008 ... in 2008 was was @loige 29
44. Today... Today... We can do better! We can do better! @loige 30
45. Updating Updating them should be easy them should be easy We shouldn't worry about We shouldn't worry about transitive dependencies transitive dependencies (dependencies of dependencies) (dependencies of dependencies) Order of imports Order of imports shouldn't really matter shouldn't really matter We rely on We rely on dependencies dependencies! ! @loige 31
46. Dependency Dependency (or coupling) a state in which one object uses a function of another object — Wikipedia @loige 32
47. Reusable dependencies... Reusable dependencies... Modules! Modules! @loige 33
48. Modules Modules The bricks for structuring non-trivial applications, but also the main mechanism to enforce information hiding by keeping private all the functions and variables that are not explicitly marked to be exported — * Node.js Design Patterns (Second Edition) * yeah, I quite like quoting my stuff... @loige 34
49. 1. Why we need modules 2. JavaScript module systems 3. How a module bundler works 4. Webpack in 2 minutes! 5. Advanced module bundling Agenda Agenda @loige 35
50. Meet my friend Meet my friend I.I.F.E. I.I.F.E. (Immediately Invoked Function Expression) loige.link/iife @loige 36
51. We generally define a function this way We generally define a function this way @loige 37
52. We generally define a function this way We generally define a function this way const sum = (a, b) => a + b @loige 37
53. We generally define a function this way We generally define a function this way const sum = (a, b) => a + b or or @loige 37
54. We generally define a function this way We generally define a function this way const sum = (a, b) => a + b function sum(a, b) { return a + b } or or @loige 37
55. We generally define a function this way We generally define a function this way const sum = (a, b) => a + b function sum(a, b) { return a + b } or or then, at some point, we execute it... then, at some point, we execute it... @loige 37
56. We generally define a function this way We generally define a function this way const sum = (a, b) => a + b function sum(a, b) { return a + b } or or then, at some point, we execute it... then, at some point, we execute it... const four = sum(2, 2) @loige 37
57. A function in JS creates an isolated scope A function in JS creates an isolated scope @loige 38
58. A function in JS creates an isolated scope A function in JS creates an isolated scope (a, b) => { const secretString = "Hello" return a + b } console.log(secretString) // undefined @loige 38
59. A function in JS creates an isolated scope A function in JS creates an isolated scope (a, b) => { const secretString = "Hello" return a + b } console.log(secretString) // undefined secretString secretString is not visible outside the function is not visible outside the function @loige 38
60. IIFE allows you to define an isolated scope IIFE allows you to define an isolated scope that executes itself that executes itself (arg1, arg2) => { // do stuff here const iAmNotVisibleOutside = true } @loige 39
61. IIFE allows you to define an isolated scope IIFE allows you to define an isolated scope that executes itself that executes itself (arg1, arg2) => { // do stuff here const iAmNotVisibleOutside = true } A function with its own scope @loige 39
62. )(someArg1, someArg2) IIFE allows you to define an isolated scope IIFE allows you to define an isolated scope that executes itself that executes itself (arg1, arg2) => { // do stuff here const iAmNotVisibleOutside = true } ( @loige 39
63. )(someArg1, someArg2) IIFE allows you to define an isolated scope IIFE allows you to define an isolated scope that executes itself that executes itself (arg1, arg2) => { // do stuff here const iAmNotVisibleOutside = true } ( This wrapper executes the function immediately and passes arguments from the outer scope @loige 39
64. IIFE is a recurring pattern in IIFE is a recurring pattern in JavaScript modules JavaScript modules @loige 40
65. Let's implement a module Let's implement a module that provides: that provides: Information hiding Information hiding exported functionalities exported functionalities @loige 41
66. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined @loige 42
67. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined @loige 42
68. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined IIFE Creates an isolated scope and executes it @loige 42
69. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined information hiding non-exported functionality @loige 42
70. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined defines exported functionalities @loige 42
71. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined propagates the exports to the outer scope (assigning it to myModule) @loige 42
72. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined Can access exported functionalities @loige 42
73. const myModule = (() => { const privateFoo = () => { /* ... */ } const privateBar = [ /* ... */ ] const exported = { publicFoo: () => { /* ... */ }, publicBar: [ /* ... */ ] }; return exported })() A module myModule.publicFoo() myModule.publicBar[0] myModule.privateFoo // undefined myModule.privateBar // undefined privateFoo // undefined privateBar // undefined No visibility for the non-exported ones @loige 42
74. We want modules to be We want modules to be reusable reusable across different apps and across different apps and organisations... organisations... ...we need ...we need A A STANDARD MODULE STANDARD MODULE format! format! @loige 43
75. Module system features Module system features Must have Simple syntax for import / export Information hiding Allows to define modules in separate files Modules can import from other modules (nested dependencies) @loige 44 . 1
76. Module system features Module system features Nice to have Ability to import module subsets Avoid naming collision Asynchronous module loading Seamless support for Browsers & Server-side @loige 44 . 2
77. JavaScript module systems JavaScript module systems globals CommonJS (Node.js) AMD (Require.js / Dojo) UMD ES2015 Modules (ESM) Many others (SystemJS, ...) @loige 45
78. Globals Globals var $, jQuery $ = jQuery = (() => { return { /* ... */ } })() // ... use $ or jQuery in the global scope $.find('.button').remove() @loige 46
79. Globals Globals Might generate naming collisions (e.g. $ overrides browser global variable) Modules needs to be "fully loaded" in the right order Cannot import parts of modules @loige 47
80. // or import single functionality const { concat } = require('./loDash') concat([1], [2], [3]) // app.js // import full module const _ = require('./loDash') _.concat([1], [2], [3]) // loDash.js const loDash = { /* ... */ } module.exports = loDash CommonJS CommonJS @loige 48
81. // or import single functionality const { concat } = require('./loDash') concat([1], [2], [3]) // app.js // import full module const _ = require('./loDash') _.concat([1], [2], [3]) // loDash.js const loDash = { /* ... */ } module.exports = loDash CommonJS CommonJS module @loige 48
82. // or import single functionality const { concat } = require('./loDash') concat([1], [2], [3]) // app.js // import full module const _ = require('./loDash') _.concat([1], [2], [3]) // loDash.js const loDash = { /* ... */ } module.exports = loDash CommonJS CommonJS module app using module @loige 48
83. // or import single functionality const { concat } = require('./loDash') concat([1], [2], [3]) // app.js // import full module const _ = require('./loDash') _.concat([1], [2], [3]) // loDash.js const loDash = { /* ... */ } module.exports = loDash CommonJS CommonJS module app using module @loige 48
84. // or import single functionality const { concat } = require('./loDash') concat([1], [2], [3]) // app.js // import full module const _ = require('./loDash') _.concat([1], [2], [3]) // loDash.js const loDash = { /* ... */ } module.exports = loDash CommonJS CommonJS module app using module @loige 48
85. CommonJS CommonJS No naming collisions (imported modules can be renamed) Huge repository of modules through Synchronous import only Works natively on the server side only (Node.js) NPM @loige 49
86. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // jquery-1.9.0.js define( 'jquery', ['sizzle', 'jqueryUI'], function (sizzle, jqueryUI) { // Returns the exported value return function () { // ... } } ) @loige 50
87. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // jquery-1.9.0.js define( 'jquery', ['sizzle', 'jqueryUI'], function (sizzle, jqueryUI) { // Returns the exported value return function () { // ... } } ) module @loige 50
88. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // jquery-1.9.0.js define( 'jquery', ['sizzle', 'jqueryUI'], function (sizzle, jqueryUI) { // Returns the exported value return function () { // ... } } ) module module name @loige 50
89. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // jquery-1.9.0.js define( 'jquery', ['sizzle', 'jqueryUI'], function (sizzle, jqueryUI) { // Returns the exported value return function () { // ... } } ) module dependencies @loige 50
90. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // jquery-1.9.0.js define( 'jquery', ['sizzle', 'jqueryUI'], function (sizzle, jqueryUI) { // Returns the exported value return function () { // ... } } ) module factory function used to construct the module, receives the dependencies as arguments @loige 50
91. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // jquery-1.9.0.js define( 'jquery', ['sizzle', 'jqueryUI'], function (sizzle, jqueryUI) { // Returns the exported value return function () { // ... } } ) module exported value @loige 50
92. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // app.js // define paths requirejs.config({ baseUrl: 'js/lib', paths: { jquery: 'jquery-1.9.0' } }) define(['jquery'], function ($) { // this is executed only when jquery // and its deps are loaded }); @loige 51
93. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // app.js // define paths requirejs.config({ baseUrl: 'js/lib', paths: { jquery: 'jquery-1.9.0' } }) define(['jquery'], function ($) { // this is executed only when jquery // and its deps are loaded }); app @loige 51
94. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // app.js // define paths requirejs.config({ baseUrl: 'js/lib', paths: { jquery: 'jquery-1.9.0' } }) define(['jquery'], function ($) { // this is executed only when jquery // and its deps are loaded }); app Require.js config jquery will be loaded from ://<currentDomain>/js/lib/jquery-1.9.0.js @loige 51
95. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js // app.js // define paths requirejs.config({ baseUrl: 'js/lib', paths: { jquery: 'jquery-1.9.0' } }) define(['jquery'], function ($) { // this is executed only when jquery // and its deps are loaded }); app app main function Has jquery as dependency @loige 51
96. AMD ( AMD ( ) ) Asynchronous Module Definition Asynchronous Module Definition Require.js Require.js Asynchronous modules Works on Browsers and Server side Very verbose and convoluted syntax (my opinion™) @loige 52
97. UMD UMD Universal Module Definition Universal Module Definition A module definition that is compatible with Global modules, CommonJS & AMD github.com/umdjs/umd @loige 53 . 1
98. (function (root, factory) { if (typeof exports === 'object') { // CommonJS module.exports = factory(require('dep')) } else if (typeof define === 'function' && define.amd) { // AMD define(['dep'], function (dep) { return (root.returnExportsGlobal = factory(dep)) }) } else { // Global Variables root.myModule = factory(root.dep) } }(this, function (dep) { // Your actual module return {} })) loige.link/umd @loige 53 . 2
99. (function (root, factory) { if (typeof exports === 'object') { // CommonJS module.exports = factory(require('dep')) } else if (typeof define === 'function' && define.amd) { // AMD define(['dep'], function (dep) { return (root.returnExportsGlobal = factory(dep)) }) } else { // Global Variables root.myModule = factory(root.dep) } }(this, function (dep) { // Your actual module return {} })) loige.link/umd IIFE with arguments: - Current scope (this) and the module factory function. - "dep" is a sample dependency of the module. @loige 53 . 2
100. (function (root, factory) { if (typeof exports === 'object') { // CommonJS module.exports = factory(require('dep')) } else if (typeof define === 'function' && define.amd) { // AMD define(['dep'], function (dep) { return (root.returnExportsGlobal = factory(dep)) }) } else { // Global Variables root.myModule = factory(root.dep) } }(this, function (dep) { // Your actual module return {} })) loige.link/umd @loige 53 . 2
101. (function (root, factory) { if (typeof exports === 'object') { // CommonJS module.exports = factory(require('dep')) } else if (typeof define === 'function' && define.amd) { // AMD define(['dep'], function (dep) { return (root.returnExportsGlobal = factory(dep)) }) } else { // Global Variables root.myModule = factory(root.dep) } }(this, function (dep) { // Your actual module return {} })) loige.link/umd @loige 53 . 2
102. (function (root, factory) { if (typeof exports === 'object') { // CommonJS module.exports = factory(require('dep')) } else if (typeof define === 'function' && define.amd) { // AMD define(['dep'], function (dep) { return (root.returnExportsGlobal = factory(dep)) }) } else { // Global Variables root.myModule = factory(root.dep) } }(this, function (dep) { // Your actual module return {} })) loige.link/umd @loige 53 . 2
103. Allows you to define modules that can be used by almost any module loader Complex, the wrapper code is almost impossible to write manually UMD UMD Universal Module Definition Universal Module Definition @loige 53 . 3
104. ES2015 modules ES2015 modules Cool & broad subject, it would deserve it's own talk Wanna know more? / syntax reference import export ECMAScript modules in browsers ES modules: A cartoon deep-dive ES Modules in Node Today! @loige 54 . 1
105. // calculator.js const add = (num1, num2) => num1 + num2 const sub = (num1, num2) => num1 - num2 const div = (num1, num2) => num1 / num2 const mul = (num1, num2) => num1 * num2 export { add, sub, div, mul } // app.js import { add } from './calculator' console.log(add(2,2)) // 4 ES2015 modules ES2015 modules @loige 54 . 2
106. // calculator.js const add = (num1, num2) => num1 + num2 const sub = (num1, num2) => num1 - num2 const div = (num1, num2) => num1 / num2 const mul = (num1, num2) => num1 * num2 export { add, sub, div, mul } // app.js import { add } from './calculator' console.log(add(2,2)) // 4 ES2015 modules ES2015 modules module @loige 54 . 2
107. // calculator.js const add = (num1, num2) => num1 + num2 const sub = (num1, num2) => num1 - num2 const div = (num1, num2) => num1 / num2 const mul = (num1, num2) => num1 * num2 export { add, sub, div, mul } // app.js import { add } from './calculator' console.log(add(2,2)) // 4 ES2015 modules ES2015 modules module exported functionalities @loige 54 . 2
108. // calculator.js const add = (num1, num2) => num1 + num2 const sub = (num1, num2) => num1 - num2 const div = (num1, num2) => num1 / num2 const mul = (num1, num2) => num1 * num2 export { add, sub, div, mul } // app.js import { add } from './calculator' console.log(add(2,2)) // 4 ES2015 modules ES2015 modules module app @loige 54 . 2
109. // calculator.js const add = (num1, num2) => num1 + num2 const sub = (num1, num2) => num1 - num2 const div = (num1, num2) => num1 / num2 const mul = (num1, num2) => num1 * num2 export { add, sub, div, mul } // app.js import { add } from './calculator' console.log(add(2,2)) // 4 ES2015 modules ES2015 modules module app import specific functionality @loige 54 . 2
110. // index.html <html> <body> <!-- ... --> <script type="module"> import { add } from 'calculator.js' console.log(add(2,2)) // 4 </script> </body> </html> ES2015 modules ES2015 modules @loige 54 . 3
111. // index.html <html> <body> <!-- ... --> <script type="module"> import { add } from 'calculator.js' console.log(add(2,2)) // 4 </script> </body> </html> ES2015 modules ES2015 modules "works" in some modern browsers @loige 54 . 3
112. ES2015 modules ES2015 modules Syntactically very similar to CommonJS... BUT import & export are static (allow static analysis of dependencies) It is a (still work in progress) standard format Works (almost) seamlessly in browsers & servers @loige 54 . 4
113. So many options... So many options... Current most used practice: Use CommonJS or ES2015 & create "compiled bundles" @loige 55
114. 1. Why we need modules 2. JavaScript module systems 3. How a module bundler works 4. Webpack in 2 minutes! 5. Advanced module bundling Agenda Agenda @loige 56
115. Let's try to use CommonJS Let's try to use CommonJS in the browser in the browser @loige 57
116. const $ = require('zepto') const tippy = require('tippy.js') const UUID = require('uuidjs') const { confetti } = require('dom-confetti/src/main') const store = require('store2') const Favico = require('favico.js') !(function () { const colors = ['#a864fd', '#29cdff', '#78ff44', '#ff718d', '#fdff6a'] const todoApp = (rootEl, opt = {}) => { const todos = opt.todos || [] let completedTasks = opt.completedTasks || 0 const onChange = opt.onChange || (() => {}) const list = rootEl.find('.todo-list') const footer = rootEl.find('.footer') const todoCount = footer.find('.todo-count') const insertInput = rootEl.find('.add-todo-box input') const insertBtn = rootEl.find('.add-todo-box button') const render = () => { let tips list.html('') The browser doesn't know how to process require. It doesn't support CommonJS! @loige 58
117. Module Bundler Module Bundler A tool that takes modules with dependencies and emits static assets representing those modules Those static assets can be processed by browsers! @loige 59
118. Dependency graph Dependency graph A graph built by connecting every module with its direct dependencies. app dependency A dependency B dependency A2 shared dependency @loige 60
119. A module bundler has to: A module bundler has to: 1. Construct the dependency graph (Dependency Resolution) 2. Assemble the modules in the graph into a single executable asset (Packing) @loige 61
120. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution 62 @loige
121. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app 62 (entrypoint) (1) @loige
122. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator 62 (entrypoint) (1) @loige
123. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator 62 (entrypoint) (1) (2) @loige
124. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator parser 62 (entrypoint) (1) (2) @loige
125. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator parser 62 (entrypoint) (1) (2) (3) @loige
126. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator parser resolver 62 (entrypoint) (1) (2) (3) @loige
127. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator parser resolver 62 (entrypoint) (1) (2) (3) (4) @loige
128. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator log parser resolver 62 (entrypoint) (1) (2) (3) (4) @loige
129. // app.js const calculator = require('./calculator') const log = require('./log') log(calculator('2 + 2 / 4')) // log.js module.exports = console.log // calculator.js const parser = require('./parser') const resolver = require('./resolver') module.exports = (expr) => resolver(parser(expr)) // parser.js module.exports = (expr) => { /* ... */ } // resolver.js module.exports = (tokens) => { /* ... */ } Dependency resolution Dependency resolution app calculator log parser resolver 62 (entrypoint) (1) (2) (3) (4) (5) @loige
130. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map @loige 63
131. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } @loige 63
132. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, @loige 63
133. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, @loige 63
134. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './parser': (module, require) => { … }, @loige 63
135. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, @loige 63
136. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, @loige 63
137. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, require path @loige 63
138. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, module factory function @loige 63
139. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, const parser = require('./parser');const resolver = require('./resolver');module.exports = (expr) => resolver(parser(expr)) @loige 63
140. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, const parser = require('./parser');const resolver = require('./resolver');module.exports = (expr) => resolver(parser(expr)) @loige 63
141. During During dependency resolution dependency resolution, , the bundler creates a the bundler creates a modules map modules map { } './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … }, const parser = require('./parser');const resolver = require('./resolver');module.exports = (expr) => resolver(parser(expr)) @loige 63
142. Packing Packing { ­­­ : ­­­ ­­­ : ­­­­ ­­­ : ­­ } Modules map Modules map @loige 64
143. Packing Packing { ­­­ : ­­­ ­­­ : ­­­­ ­­­ : ­­ } Modules map Modules map @loige 64
144. Packing Packing .js { ­­­ : ­­­ ­­­ : ­­­­ ­­­ : ­­ } Modules map Modules map Single executable Single executable JS file JS file @loige 64
145. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) 65 @loige
146. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) IIFE passing the modules map as argument 65 @loige
147. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) Custom require function: it will load the modules by evaluating the code from the modules map 65 @loige
148. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) A reference to a module with an empty module.exports. This will be filled at evaluation time 65 @loige
149. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) Invoking the factory function for the given module name. (Service locator pattern) 65 @loige
150. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) The current reference module is passed, the factory function will modify this object by adding the proper exported values. 65 @loige
151. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) The custom require function is passed so, modules can recursively require other modules 65 @loige
152. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) The resulting module.exports is returned 65 @loige
153. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) The entrypoint module is required, triggering the actual execution of the business logic 65 @loige
154. Packed executable file Packed executable file ((modulesMap) => { const require = (name) => { const module = { exports: {} } modulesMap[name](module, require) return module.exports } require('./app') })( { './app': (module, require) => { … }, './calculator': (module, require) => { … }, './log': (module, require) => { … }, './parser': (module, require) => { … }, './resolver': (module, require) => { … } } ) 65 @loige
155. Now you know how Now you know how Module bundlers work! Module bundlers work! And how to convert code written And how to convert code written using using CommonJS CommonJS to a single file that to a single file that works in the browser works in the browser @loige 66
156. A challenge for you! A challenge for you! If you do, ... I'll arrange a prize for you! TIP: you can use or to parse JavaScript files (look for require and module.exports) and to map relative module paths to actual files in the filesystem. Need an inspiration? Check the awesome and ! let me know acorn babel-parser resolve minipack @adamisnotdead's w_bp_ck Can you build a (simple) module bundler from scratch? Can you build a (simple) module bundler from scratch? @loige 67
157. 1. Why we need modules 2. JavaScript module systems 3. How a module bundler works 4. Webpack in 2 minutes! 5. Advanced module bundling Agenda Agenda @loige 68
158. A state of the art module A state of the art module bundler for the web bundler for the web @loige 69
159. npm install webpack webpack­cli @loige 70
160. webpack app.js yep, recent versions of Webpack work without config! @loige 71
161. webpack ­­mode=development app.js Do not compress the code and add annotations! @loige 72
162. loige.link/sample-webpacked-file @loige 73
163. Webpack concepts Webpack concepts Entry point: the starting file for dependency resolution. Output: the destination file (bundled file). Loaders: algorithms to parse different file types and convert them into executable javascript (e.g. babel, typescript, but also CSS, images or other static assets) Plugins: do extra things (e.g. generate a wrapping HTML or analysis tools) @loige 74
164. const { resolve, join } = require('path') const CompressionPlugin = require('compression-webpack-plugin') module.exports = { entry: './app.js', output: { path: resolve(join(__dirname, 'build')), filename: 'app.js' }, module: { rules: [ { test: /\.js$/, exclude: /(node_modules|bower_components)/, use: { loader: 'babel-loader', options: { presets: [ ['@babel/preset-env'] ] } } } ] }, plugins: [ new CompressionPlugin() ] } Webpack.config.js @loige 75
165. const { resolve, join } = require('path') const CompressionPlugin = require('compression-webpack-plugin') module.exports = { entry: './app.js', output: { path: resolve(join(__dirname, 'build')), filename: 'app.js' }, module: { rules: [ { test: /\.js$/, exclude: /(node_modules|bower_components)/, use: { loader: 'babel-loader', options: { presets: [ ['@babel/preset-env'] ] } } } ] }, plugins: [ new CompressionPlugin() ] } Webpack.config.js Entrypoint Build the dependency graph starting from ./app.js @loige 75
166. const { resolve, join } = require('path') const CompressionPlugin = require('compression-webpack-plugin') module.exports = { entry: './app.js', output: { path: resolve(join(__dirname, 'build')), filename: 'app.js' }, module: { rules: [ { test: /\.js$/, exclude: /(node_modules|bower_components)/, use: { loader: 'babel-loader', options: { presets: [ ['@babel/preset-env'] ] } } } ] }, plugins: [ new CompressionPlugin() ] } Webpack.config.js Output Save the resulting bundled file in ./build/app.js @loige 75
167. const { resolve, join } = require('path') const CompressionPlugin = require('compression-webpack-plugin') module.exports = { entry: './app.js', output: { path: resolve(join(__dirname, 'build')), filename: 'app.js' }, module: { rules: [ { test: /\.js$/, exclude: /(node_modules|bower_components)/, use: { loader: 'babel-loader', options: { presets: [ ['@babel/preset-env'] ] } } } ] }, plugins: [ new CompressionPlugin() ] } Webpack.config.js Loaders All the files matching "*.js" are processed with babel and converted to ES5 Javascript @loige 75
168. const { resolve, join } = require('path') const CompressionPlugin = require('compression-webpack-plugin') module.exports = { entry: './app.js', output: { path: resolve(join(__dirname, 'build')), filename: 'app.js' }, module: { rules: [ { test: /\.js$/, exclude: /(node_modules|bower_components)/, use: { loader: 'babel-loader', options: { presets: [ ['@babel/preset-env'] ] } } } ] }, plugins: [ new CompressionPlugin() ] } Webpack.config.js Plugins Uses a plugin that generates a gzipped copy of every emitted file. @loige 75
169. Everything is a module Everything is a module import React, { Component } from 'react' import logo from './logo.svg' import './App.css' class App extends Component { render() { return ( <div className="App"> <header className="App-header"> <img src={logo} className="App-logo" alt="logo" /> <h1 className="App-title">Welcome to React</h1> </header> </div> ); } } export default App 76
170. Everything is a module Everything is a module import React, { Component } from 'react' import logo from './logo.svg' import './App.css' class App extends Component { render() { return ( <div className="App"> <header className="App-header"> <img src={logo} className="App-logo" alt="logo" /> <h1 className="App-title">Welcome to React</h1> </header> </div> ); } } export default App 76
171. Everything is a module Everything is a module import React, { Component } from 'react' import logo from './logo.svg' import './App.css' class App extends Component { render() { return ( <div className="App"> <header className="App-header"> <img src={logo} className="App-logo" alt="logo" /> <h1 className="App-title">Welcome to React</h1> </header> </div> ); } } export default App 76
172. Everything is a module Everything is a module import React, { Component } from 'react' import logo from './logo.svg' import './App.css' class App extends Component { render() { return ( <div className="App"> <header className="App-header"> <img src={logo} className="App-logo" alt="logo" /> <h1 className="App-title">Welcome to React</h1> </header> </div> ); } } export default App 76
173. Webpack can load any type of file Webpack can load any type of file As long as you can provide a " As long as you can provide a "loader loader" that " that tells how to convert the file into tells how to convert the file into something the browser understands. something the browser understands. This is how Webpack allows you to use Babel, TypeScript, Clojure, Elm, Imba but also to load CSSs, Images and other assets. 77
174. { test: /\.css$/, use: [ require.resolve('style-loader'), { loader: require.resolve('css-loader'), options: { importLoaders: 1, }, }, { loader: require.resolve('postcss-loader'), options: { ident: 'postcss', plugins: () => [ require('postcss-flexbugs-fixes'), autoprefixer({ browsers: [ '>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', 78
175. { test: /\.css$/, use: [ require.resolve('style-loader'), { loader: require.resolve('css-loader'), options: { importLoaders: 1, }, }, { loader: require.resolve('postcss-loader'), options: { ident: 'postcss', plugins: () => [ require('postcss-flexbugs-fixes'), autoprefixer({ browsers: [ '>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', // Defines how to load .css files (uses a pipeline of loaders) 78
176. { test: /\.css$/, use: [ require.resolve('style-loader'), { loader: require.resolve('css-loader'), options: { importLoaders: 1, }, }, { loader: require.resolve('postcss-loader'), options: { ident: 'postcss', plugins: () => [ require('postcss-flexbugs-fixes'), autoprefixer({ browsers: [ '>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', // Defines how to load .css files (uses a pipeline of loaders) // parses the file with post-css 78
177. { test: /\.css$/, use: [ require.resolve('style-loader'), { loader: require.resolve('css-loader'), options: { importLoaders: 1, }, }, { loader: require.resolve('postcss-loader'), options: { ident: 'postcss', plugins: () => [ require('postcss-flexbugs-fixes'), autoprefixer({ browsers: [ '>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', // Defines how to load .css files (uses a pipeline of loaders) // parses the file with post-css // process @import and url() // statements 78
178. { test: /\.css$/, use: [ require.resolve('style-loader'), { loader: require.resolve('css-loader'), options: { importLoaders: 1, }, }, { loader: require.resolve('postcss-loader'), options: { ident: 'postcss', plugins: () => [ require('postcss-flexbugs-fixes'), autoprefixer({ browsers: [ '>1%', 'last 4 versions', 'Firefox ESR', 'not ie < 9', // Defines how to load .css files (uses a pipeline of loaders) // parses the file with post-css // process @import and url() // statements // inject the resulting code with a <style> tag 78
179. ...Webpack can do (a lot) more! ...Webpack can do (a lot) more! Dev Server Dev Server Tree shaking Tree shaking Dependencies analytics Dependencies analytics Source maps Source maps Async require / module splitting Async require / module splitting @loige 79
180. 1. Why we need modules 2. JavaScript module systems 3. How a module bundler works 4. Webpack in 2 minutes! 5. Advanced module bundling Agenda Agenda @loige 80
181. Bundle cache busting Bundle cache busting Device CDN Origin Server bundle.js (original) 81
182. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js (original) 81
183. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js (original) 81
184. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js bundle.js (original) 81
185. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js bundle.js (original) 81
186. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js bundle.js (original) bundle.js (cache copy) 81
187. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js bundle.js (original) bundle.js (cache copy) 81
188. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js bundle.js (original) bundle.js (cache copy) 81 bundle.js (cache copy)
189. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js 82 bundle.js (original) bundle.js (cache copy) bundle.js (cache copy)
190. Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js 82 bundle.js (original) bundle.js (cache copy) bundle.js (cache copy) NEW VERSION
191. STALE! Bundle cache busting Bundle cache busting Device CDN Origin Server example.com bundle.js bundle.js 82 bundle.js (original) bundle.js (cache copy) bundle.js (cache copy) NEW VERSION STALE!
192. Bundle cache busting Bundle cache busting 83
193. Bundle cache busting Bundle cache busting (Manual) Solution 1 (Manual) Solution 1 83
194. Bundle cache busting Bundle cache busting (Manual) Solution 1 (Manual) Solution 1 bundle.js?v=1 bundle.js?v=2 bundle.js?v=3 83
195. Bundle cache busting Bundle cache busting (Manual) Solution 1 (Manual) Solution 1 bundle.js?v=1 bundle.js?v=2 bundle.js?v=3 Doesn't play nice with some CDNs and Proxies (they won't consider different query parameters to be different resources) 83
196. Bundle cache busting Bundle cache busting 84
197. Bundle cache busting Bundle cache busting (Manual) Solution 2 (Manual) Solution 2 84
198. Bundle cache busting Bundle cache busting (Manual) Solution 2 (Manual) Solution 2 bundle-v1.js bundle-v2.js bundle-v3.js ... 84
199. Bundle cache busting Bundle cache busting (Manual) Solution 2 (Manual) Solution 2 bundle-v1.js bundle-v2.js bundle-v3.js ... Better, but still a lot of diligence and manual effort needed... 84
200. Bundle cache busting Bundle cache busting 85
201. Bundle cache busting Bundle cache busting Webpack Solution Webpack Solution 85
202. Bundle cache busting Bundle cache busting Webpack Solution Webpack Solution output: { filename: '[name].[contenthash].js' } 85
203. Bundle cache busting Bundle cache busting Webpack Solution Webpack Solution ... bundle.9f61f58dd1cc3bb82182.js bundle.aacdf58ef1aa12382199.js bundle.ed61f68defef3bb82221.js output: { filename: '[name].[contenthash].js' } 85
204. Bundle cache busting Bundle cache busting Webpack Solution Webpack Solution + Every new asset version will generate a new file cache is automatically cleaned up on every release (if content actually changed) html-plugin will update the reference to the new file contenthash webpack-html-plugin 86
205. 1. Why we need modules 2. JavaScript module systems 3. How a module bundler works 4. Webpack in 2 minutes! 5. Advanced module bundling Agenda Agenda @loige 87
206. Module bundlers are your friends Module bundlers are your friends Now you know how they work, they are not (really) magic! Start small and add more when needed If you try to build your own, you'll learn a lot more! @loige 88
207. Webpack is not Webpack is not the only possibility! the only possibility! 89
208. Ευχαριστώ! Ευχαριστώ! Special thanks: , , , (reviewers) and (inspirations: his and his ) @Podgeypoos79 @andreaman87 @mariocasciaro @eugenserbanescu @MarijnJH amazing book workshop on JS modules @loige Images by cover Image by from Streamline Emoji pack Dimitris Vetsikas Pixabay loige.link/bundle-devit 90