├── .github └── FUNDING.yml ├── .gitignore ├── .prettierrc ├── .travis.yml ├── README.md ├── package-lock.json ├── package.json ├── public ├── favicon.ico ├── index.html └── manifest.json └── src ├── App.js ├── App.test.js ├── index.js └── registerServiceWorker.js /.github/FUNDING.yml: -------------------------------------------------------------------------------- 1 | # These are supported funding model platforms 2 | 3 | github: rwieruch 4 | patreon: # rwieruch 5 | open_collective: # Replace with a single Open Collective username 6 | ko_fi: # Replace with a single Ko-fi username 7 | tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel 8 | community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry 9 | liberapay: # Replace with a single Liberapay username 10 | issuehunt: # Replace with a single IssueHunt username 11 | otechie: # Replace with a single Otechie username 12 | custom: # Replace with a single custom sponsorship URL 13 | -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # See https://help.github.com/ignore-files/ for more about ignoring files. 2 | 3 | # dependencies 4 | /node_modules 5 | 6 | # testing 7 | /coverage 8 | 9 | # production 10 | /build 11 | 12 | # misc 13 | .DS_Store 14 | .env.local 15 | .env.development.local 16 | .env.test.local 17 | .env.production.local 18 | 19 | npm-debug.log* 20 | yarn-debug.log* 21 | yarn-error.log* 22 | -------------------------------------------------------------------------------- /.prettierrc: -------------------------------------------------------------------------------- 1 | { 2 | "semi": true, 3 | "trailingComma": "all", 4 | "singleQuote": true, 5 | "printWidth": 70, 6 | } -------------------------------------------------------------------------------- /.travis.yml: -------------------------------------------------------------------------------- 1 | language: node_js 2 | 3 | node_js: 4 | - stable 5 | 6 | install: 7 | - npm install 8 | 9 | script: 10 | - npm test 11 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # react-prevent-rerender-component 2 | 3 | [![Build Status](https://travis-ci.org/the-road-to-learn-react/react-prevent-rerender-component.svg?branch=master)](https://travis-ci.org/the-road-to-learn-react/react-prevent-rerender-component) [![Slack](https://slack-the-road-to-learn-react.wieruch.com/badge.svg)](https://slack-the-road-to-learn-react.wieruch.com/) [![Greenkeeper badge](https://badges.greenkeeper.io/the-road-to-learn-react/react-prevent-rerender-component.svg)](https://greenkeeper.io/) 4 | 5 | An application showcasing how to prevent a rerender of a React component with shouldComponentUpdate or PureComponent in React. It is used for performance optimizations in update lifecycles (e.g. render). [Read more about it](https://www.robinwieruch.de/react-prevent-rerender-component). 6 | 7 | ## Features 8 | 9 | * performance optimization 10 | * React's shouldComponentUpdate 11 | * React's PureComponent 12 | * [recompose](https://github.com/acdlite/recompose)'s pure 13 | 14 | ## Installation 15 | 16 | * `git clone git@github.com:the-road-to-learn-react/react-prevent-rerender-component.git` 17 | * cd react-prevent-rerender-component 18 | * npm install 19 | * npm start 20 | * visit `http://localhost:3000` 21 | -------------------------------------------------------------------------------- /package.json: -------------------------------------------------------------------------------- 1 | { 2 | "name": "react-pure-component-example", 3 | "version": "0.1.0", 4 | "private": true, 5 | "dependencies": { 6 | "react": "^16.5.0", 7 | "react-dom": "^16.5.0", 8 | "react-scripts": "3.1.0", 9 | "recompose": "^0.30.0", 10 | "styled-components": "^4.0.2" 11 | }, 12 | "scripts": { 13 | "start": "react-scripts start", 14 | "build": "react-scripts build", 15 | "test": "react-scripts test --env=jsdom", 16 | "eject": "react-scripts eject" 17 | } 18 | } 19 | -------------------------------------------------------------------------------- /public/favicon.ico: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/the-road-to-learn-react/react-prevent-rerender-component/e33e446636dc81b6cb4cb38df277c6c58eba15fc/public/favicon.ico -------------------------------------------------------------------------------- /public/index.html: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | 7 | 11 | 12 | 13 | 22 | React App 23 | 24 | 25 | 28 |
29 | 39 | 40 | 41 | -------------------------------------------------------------------------------- /public/manifest.json: -------------------------------------------------------------------------------- 1 | { 2 | "short_name": "React App", 3 | "name": "Create React App Sample", 4 | "icons": [ 5 | { 6 | "src": "favicon.ico", 7 | "sizes": "64x64 32x32 24x24 16x16", 8 | "type": "image/x-icon" 9 | } 10 | ], 11 | "start_url": "./index.html", 12 | "display": "standalone", 13 | "theme_color": "#000000", 14 | "background_color": "#ffffff" 15 | } 16 | -------------------------------------------------------------------------------- /src/App.js: -------------------------------------------------------------------------------- 1 | import React, { Component, PureComponent } from 'react'; 2 | import styled from 'styled-components'; 3 | import { pure } from 'recompose'; 4 | 5 | const list = new Array(5000).fill(0).map((v, i) => i); 6 | 7 | class App extends Component { 8 | state = { 9 | perspective: false, 10 | }; 11 | 12 | togglePerspective = () => { 13 | this.setState(state => ({ perspective: !state.perspective })); 14 | }; 15 | 16 | render() { 17 | return ( 18 |
19 | 22 | 23 | 24 | {list.map(v => )} 25 | 26 |
27 | ); 28 | } 29 | } 30 | 31 | const Perspective = styled.div` 32 | display: flex; 33 | flex-wrap: wrap; 34 | flex-direction: ${props => (props.perspective ? 'row' : 'column')}; 35 | `; 36 | 37 | const Button = ({ onClick, children }) => ( 38 | 41 | ); 42 | 43 | const Item = styled.div` 44 | margin: 10px; 45 | `; 46 | 47 | // Different versions: 48 | 49 | // FAST, no re-render, shallow shouldComponentUpdate check 50 | const Square = pure(({ number }) => {number * number}); 51 | 52 | // FAST, no re-render, shallow shouldComponentUpdate check 53 | // class Square extends PureComponent { 54 | // render() { 55 | // return {this.props.number * this.props.number}; 56 | // } 57 | // } 58 | 59 | // FAST, no re-render, fine-granular shouldComponentUpdate check 60 | // class Square extends Component { 61 | // shouldComponentUpdate(nextProps, nextState) { 62 | // if (this.props.number === nextProps.number) { 63 | // return false; 64 | // } else { 65 | // return true; 66 | // } 67 | // } 68 | 69 | // render() { 70 | // return {this.props.number * this.props.number}; 71 | // } 72 | // } 73 | 74 | // SLOW 75 | // class Square extends Component { 76 | // render() { 77 | // return {this.props.number * this.props.number}; 78 | // } 79 | // } 80 | 81 | // SLOW 82 | // const Square = ({ number }) => {number * number}; 83 | 84 | export default App; 85 | -------------------------------------------------------------------------------- /src/App.test.js: -------------------------------------------------------------------------------- 1 | import React from 'react'; 2 | import ReactDOM from 'react-dom'; 3 | import App from './App'; 4 | 5 | it('renders without crashing', () => { 6 | const div = document.createElement('div'); 7 | ReactDOM.render(, div); 8 | ReactDOM.unmountComponentAtNode(div); 9 | }); 10 | -------------------------------------------------------------------------------- /src/index.js: -------------------------------------------------------------------------------- 1 | import React from 'react'; 2 | import ReactDOM from 'react-dom'; 3 | import App from './App'; 4 | import registerServiceWorker from './registerServiceWorker'; 5 | 6 | ReactDOM.render(, document.getElementById('root')); 7 | registerServiceWorker(); 8 | -------------------------------------------------------------------------------- /src/registerServiceWorker.js: -------------------------------------------------------------------------------- 1 | // In production, we register a service worker to serve assets from local cache. 2 | 3 | // This lets the app load faster on subsequent visits in production, and gives 4 | // it offline capabilities. However, it also means that developers (and users) 5 | // will only see deployed updates on the "N+1" visit to a page, since previously 6 | // cached resources are updated in the background. 7 | 8 | // To learn more about the benefits of this model, read https://goo.gl/KwvDNy. 9 | // This link also includes instructions on opting out of this behavior. 10 | 11 | const isLocalhost = Boolean( 12 | window.location.hostname === 'localhost' || 13 | // [::1] is the IPv6 localhost address. 14 | window.location.hostname === '[::1]' || 15 | // 127.0.0.1/8 is considered localhost for IPv4. 16 | window.location.hostname.match( 17 | /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/ 18 | ) 19 | ); 20 | 21 | export default function register() { 22 | if (process.env.NODE_ENV === 'production' && 'serviceWorker' in navigator) { 23 | // The URL constructor is available in all browsers that support SW. 24 | const publicUrl = new URL(process.env.PUBLIC_URL, window.location); 25 | if (publicUrl.origin !== window.location.origin) { 26 | // Our service worker won't work if PUBLIC_URL is on a different origin 27 | // from what our page is served on. This might happen if a CDN is used to 28 | // serve assets; see https://github.com/facebookincubator/create-react-app/issues/2374 29 | return; 30 | } 31 | 32 | window.addEventListener('load', () => { 33 | const swUrl = `${process.env.PUBLIC_URL}/service-worker.js`; 34 | 35 | if (isLocalhost) { 36 | // This is running on localhost. Lets check if a service worker still exists or not. 37 | checkValidServiceWorker(swUrl); 38 | 39 | // Add some additional logging to localhost, pointing developers to the 40 | // service worker/PWA documentation. 41 | navigator.serviceWorker.ready.then(() => { 42 | console.log( 43 | 'This web app is being served cache-first by a service ' + 44 | 'worker. To learn more, visit https://goo.gl/SC7cgQ' 45 | ); 46 | }); 47 | } else { 48 | // Is not local host. Just register service worker 49 | registerValidSW(swUrl); 50 | } 51 | }); 52 | } 53 | } 54 | 55 | function registerValidSW(swUrl) { 56 | navigator.serviceWorker 57 | .register(swUrl) 58 | .then(registration => { 59 | registration.onupdatefound = () => { 60 | const installingWorker = registration.installing; 61 | installingWorker.onstatechange = () => { 62 | if (installingWorker.state === 'installed') { 63 | if (navigator.serviceWorker.controller) { 64 | // At this point, the old content will have been purged and 65 | // the fresh content will have been added to the cache. 66 | // It's the perfect time to display a "New content is 67 | // available; please refresh." message in your web app. 68 | console.log('New content is available; please refresh.'); 69 | } else { 70 | // At this point, everything has been precached. 71 | // It's the perfect time to display a 72 | // "Content is cached for offline use." message. 73 | console.log('Content is cached for offline use.'); 74 | } 75 | } 76 | }; 77 | }; 78 | }) 79 | .catch(error => { 80 | console.error('Error during service worker registration:', error); 81 | }); 82 | } 83 | 84 | function checkValidServiceWorker(swUrl) { 85 | // Check if the service worker can be found. If it can't reload the page. 86 | fetch(swUrl) 87 | .then(response => { 88 | // Ensure service worker exists, and that we really are getting a JS file. 89 | if ( 90 | response.status === 404 || 91 | response.headers.get('content-type').indexOf('javascript') === -1 92 | ) { 93 | // No service worker found. Probably a different app. Reload the page. 94 | navigator.serviceWorker.ready.then(registration => { 95 | registration.unregister().then(() => { 96 | window.location.reload(); 97 | }); 98 | }); 99 | } else { 100 | // Service worker found. Proceed as normal. 101 | registerValidSW(swUrl); 102 | } 103 | }) 104 | .catch(() => { 105 | console.log( 106 | 'No internet connection found. App is running in offline mode.' 107 | ); 108 | }); 109 | } 110 | 111 | export function unregister() { 112 | if ('serviceWorker' in navigator) { 113 | navigator.serviceWorker.ready.then(registration => { 114 | registration.unregister(); 115 | }); 116 | } 117 | } 118 | --------------------------------------------------------------------------------