Demystifying React for Symfony developers

SymfonyCon Amsterdam 2019

Transcript

1. Demystifying React for Symfony developers Titouan GALOPIN
2. 2 Titouan Galopin Product Manager SymfonyInsight insight.symfony.com
3. Agenda 1. What’s React? 2. Components 3. Symfony integration with Webpack Encore 3
4. 4 1. What’s React?
5. 5 How should we structure Javascript applications?
6. 6 AngularJS Vue Backbone.js Dart Ember.js Dojo Meteor ...
7. 7 There is a consensus here: MVC, or MVVM, or MVW, ...
8. 8 Models
9. 9 { firstName: 'Titouan', lastName: 'Galopin', email: 'titouan.galopin@symfony.com' }
10. 10 Models = Observable objects
11. 11 Bidirectional data-binding An change in the model updates the view An change in the view updates the model
12. 12 Two data sources Model View
13. 13 This encourages mutations
14. 14 { firstName: 'Tito', lastName: 'Galopin', email: 'titouan.galopin@symfony.com' } Model { firstName: 'Titouan''Tito', lastName: 'Galopin', email: 'titouan.galopin@symfony.com' } View { firstName: 'Tito' } Mutation
15. 15 But mutations are complex
16. 16 Complex to apply Complex to reproduce Complex to debug
17. 17 What if we could do better?
18. 18 The simplest way to build views is to avoid mutations altogether
19. 19 React does not use mutations at all
20. 20 Instead, it has a single data source
21. 21 Model View Observable model Two-way data flow
22. 22 Model Observable model Two-way data flow View React One-way data flow Model Dispatcher View
23. View 23 Model Observable model Two-way data flow View React One-way data flow Model Dispatcher View
24. 24 Model Observable model Two-way data flow View React One-way data flow Model Dispatcher View
25. 25 But isn’t that super slow? What about user inputs?
26. 26 We want the benefits to blow the view away and re-render it ... … while dealing properly with every edge cases
27. 27 That’s React
28. 28 React is a Javascript library for building User Interfaces
29. 29 React is declarative render(data: array) => view: string
30. 30 React re-renders all your view when data changes
31. 31 2. Components
32. 32 React’s main concept is Components
33. 33 A component = A description of a part of your UI that depends on your current model
34. 34 It’s more than a template though
35. 35 Store Dispatcher View Each component has its own model and behavior This is component
36. 36 The aim? Abstract away the implementation details of parts of the UI
38. 38 <Autocomplete source="/api/users" onSelect={this.handleUserSelected} />
39. 39 <Autocomplete source="/api/users" onSelect={this.handleUserSelected} /> Property
40. 40 But how does it work?
41. 41 A component = A state + A way to display that state
42. 42 Store (Model) Dispatcher View React handles the Dispatcher and the Store You only implement the view and define the structure of the Store
43. 43 The state is a single Javascript object
44. 44 The view is described by a single render() function
45. 45 Store (state) Initial state
46. 46 render Store (state) View (components) Initial state
48. 48 class Autocomplete extends Component { constructor() { this.state = { results: [] }; } }
49. 49 class Autocomplete extends Component { // ... render() { return ( <ul> {this.state.results.map(function(result) { return ( <li>{result.name}</li> ); })} </ul> ); } }
50. 50 class Autocomplete extends Component { // ... render() { return ( <ul> {this.state.results.map(function(result) { return ( <li>{result.name}</li> ); })} </ul> ); } } Use of the state
51. 51 class Autocomplete extends Component { // ... render() { return ( <ul> {this.state.results.map(function(result) { return ( <li>{result.name}</li> ); })} </ul> ); } } Use of the state To use a property: this.props.source
52. State = Local data that will change over time Props = Non-local data, read-only for the component 52
53. If either the state or the properties change, the component will be re-rendered 53
54. 54 class Autocomplete extends Component { // ... render() { return ( <ul> {this.state.results.map(function(result) { return ( <li>{result.name}</li> ); })} </ul> ); } }
55. 55 class Autocomplete extends Component { // ... render() { return ( <ul> {this.state.results.map(function(result) { return ( <li>{result.name}</li> ); })} </ul> ); } } What’s that?!
56. 56 JSX is a formatting language used by React to express a representation of views
57. 57 It is compiled to Javascript <li className="hello"> becomes React.DOM.li({ className: 'hello'})
58. 58 class Autocomplete extends Component { // ... render() { return ( <ul> {this.state.results.map(function(result) { return ( <li>{result.name}</li> ); })} </ul> ); } } Not real HTML tags but components
59. 59 render() returns a tree of components
60. 60 You usually create your own tree of components RegistrationForm CityAutocompleteInput PhoneNumberInput HTMLTextInput HTMLTelInput
61. 61 Now, how to update the view?
62. 62 Instead of updates (mutations) React uses reconciliation
63. 63 setState()
64. 64 React compares the view representations and apply the changes to the DOM
65. Tree of components before change Tree of components after change setState
66. 66 Tree of components before change Tree of components after change setState render render View before View after
67. 67 Tree of components before change Tree of components after change setState render render View before View after React compares both and apply only needed changes to the DOM
68. 68 class Autocomplete extends Component { // ... handleChange(event) { api.fetchResults(event.target.value).then(results => { this.setState({ results: results }) }); } // ... render() { return ( <div> <input type="text" onChange={this.handleChange} /> // ... </div> ); } }
69. 69 setState() merges the current state and the given data ...
70. 70 … then calls recursively render() on the component and all its children
71. 71 render Store (state) View (components) Initial state
72. 72 Dispatcher (React) setState render Store (state) View (components) Initial state
73. 73 Dispatcher (React) setState render Handled by React Store (state) View (components) Initial state
74. 74 Now you know React!
75. 75 3. Symfony integration with Webpack Encore
76. 76 Webpack is a build tool It lets you manipulate your Javascript and CSS before using it in production (JSX, minification, …)
77. 77 Webpack Encore wraps Webpack around a nice API to improve its Developer Experience
78. 78 Webpack Encore is awesome to compile React apps to normal Javascript
79. 79 composer req --dev webpack yarn install https://symfony.com/doc/current/frontend.html
80. 80 yarn add @babel/preset-react react react-dom prop-types
81. 81 // webpack.config.js const Encore = require( '@symfony/webpack-encore' ); Encore // ... .enableReactPreset(); module.exports = Encore.getWebpackConfig();
82. 82 Once Webpack Encore is ready, you can use it in Twig to load React
83. 83 // index.html.twig ... <div id="portfolio"></div> … // Output proper <script src="..."> tags {{ encore_entry_script_tags('app') }}
84. 84 // app.js import ReactDOM from 'react-dom'; import {App} from './App.js'; ReactDOM.render( <App />, document.getElementById('portfolio') );
85. 85 // app.js import ReactDOM from 'react-dom'; import {App} from './App.js'; ReactDOM.render( <App />, document.getElementById('portfolio') ); Tree of components
86. 86 And that’s all! You can now use React into Symfony
87. 87 Conclusion
88. Thanks! 88 For any question: ▪ @titouangalopin on Twitter ▪ titouan.galopin @symfony.com