Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
React Hooks
Search
Matija Marohnić
December 13, 2019
Programming
0
69
React Hooks
Matija Marohnić
December 13, 2019
Tweet
Share
More Decks by Matija Marohnić
See All by Matija Marohnić
Introduction to Remix
silvenon
0
130
Cypress vs. Playwright
silvenon
0
150
Studying Strapi: an open source head headless CMS
silvenon
0
33
CSS Specificity
silvenon
0
28
Make your JavaScript projects more accessible to newcomers
silvenon
0
72
PostCSS
silvenon
0
42
CSS Custom Properties
silvenon
0
39
Maintainable Integration Testing in React
silvenon
0
29
Writing Codemods with jscodeshift
silvenon
0
27
Other Decks in Programming
See All in Programming
Webの外へ飛び出せ NativePHPが切り拓くPHPの未来
takuyakatsusa
2
340
Julia という言語について (FP in Julia « SIDE: F ») for 関数型まつり2025
antimon2
3
980
C++20 射影変換
faithandbrave
0
520
なぜ適用するか、移行して理解するClean Architecture 〜構造を超えて設計を継承する〜 / Why Apply, Migrate and Understand Clean Architecture - Inherit Design Beyond Structure
seike460
PRO
1
660
Team topologies and the microservice architecture: a synergistic relationship
cer
PRO
0
1k
Gleamという選択肢
comamoca
6
760
Rubyでやりたい駆動開発 / Ruby driven development
chobishiba
1
360
既存デザインを変更せずにタップ領域を広げる方法
tahia910
1
240
VS Code Update for GitHub Copilot
74th
1
310
Haskell でアルゴリズムを抽象化する / 関数型言語で競技プログラミング
naoya
17
4.9k
すべてのコンテキストを、 ユーザー価値に変える
applism118
2
720
都市をデータで見るってこういうこと PLATEAU属性情報入門
nokonoko1203
1
560
Featured
See All Featured
How to Ace a Technical Interview
jacobian
277
23k
The Pragmatic Product Professional
lauravandoore
35
6.7k
Evolution of real-time – Irina Nazarova, EuRuKo, 2024
irinanazarova
8
790
The MySQL Ecosystem @ GitHub 2015
samlambert
251
13k
Reflections from 52 weeks, 52 projects
jeffersonlam
351
20k
Intergalactic Javascript Robots from Outer Space
tanoku
271
27k
CSS Pre-Processors: Stylus, Less & Sass
bermonpainter
357
30k
Build The Right Thing And Hit Your Dates
maggiecrowley
36
2.8k
Making the Leap to Tech Lead
cromwellryan
134
9.3k
Measuring & Analyzing Core Web Vitals
bluesmoon
7
490
Fantastic passwords and where to find them - at NoRuKo
philnash
51
3.3k
Fireside Chat
paigeccino
37
3.5k
Transcript
React Hooks
React Hooks • released in React 16.8 • a new
way to “hook into” React features • but first, let’s recap the API we have now
Class components
function MyComponent() { return <input type="email" "/> }
class MyComponent extends React.Component { state = { email: ''
} render() { return ( <input type="email" value={this.state.email} onChange={event "=> { this.setState({ email: event.target.value, }) }} "/> ); } }
function MyComponent({ value, onChange }) { return ( <input type="email"
value={value} onChange={onChange} "/> ) }
Pros • custom methods • reusing logic • naming logic
Cons • switching back and forth between functions and classes
• a lot of typing • noisy Git diffs • class components are weird • we don’t instantiate them • we don’t extend them
Lifecycle methods
class MyComponent extends React.Component { constructor(props) static getDerivedStateFromProps(props, state) render()
componentDidMount() shouldComponentUpdate(nextProps, nextState) getSnapshotBeforeUpdate(prevProps, prevState) componentDidUpdate(prevProps, prevState, snapshot) componentWillUnmount() }
Pros • transparency • descriptive method names • API is
well documented • fine-grained control • easily target exact moment in the lifecycle
Cons • no way to escape the complexity • memorizing
common pitfalls like endless loops • spreading a single feature across multiple methods
Higher-order components (HOCs)
import email from './hocs/email' function MyComponent({ email, handleEmailChange }) {
return ( <input type="email" value={email} onChange={handleEmailChange} "/> ) } export default email(MyComponent)
Pros • reusing complex behavior • we can keep using
function components
Cons • readability • all props are mixed together •
the HOC call is usually the last thing we see
Ok, back to hooks
None
Hooks • can only be used in function components •
they represent a new mental model
Lifecycle methods
Basic hooks • useState for local state • useEffect for
side-effects • useContext for applying context
import React from 'react' function MyComponent() { const [email, setEmail]
= React.useState('') return ( <input type="email" value={email} onChange={event "=> { setEmail(event.target.value) }} "/> ) }
Stateless or function components?
import React from 'react' function MyComponent() { React.useEffect(() "=> {
console.log('mounted') return () "=> { console.log('unmounted') } }, []) return "// ""... }
A must-read: A Complete Guide to useEffect by Dan Abramov
Additional hooks • useMemo for memoizing a computed value •
useCallback for memoizing a function reference • etc. https://reactjs.org/docs/hooks-reference.html
import React from 'react' import { computeExpensiveValue } from './utils/slow'
function MyComponent({ id }) { const value = React.useMemo(() "=> { return computeExpensiveValue(id) }, [id]) return "// ""... }
Read before memoizing • One simple trick to optimize React
re-renders • When to useMemo and useCallback
Custom hooks
import React from 'react' function useModal() { const CLASS_NAME =
'modal-open' React.useEffect(() "=> { document.body.classList.add(CLASS_NAME) return () "=> { document.body.classList.remove(CLASS_NAME) } }, []) }
Custom hooks recipes: usehooks.com
eslint-plugin-react-hooks
yarn install "--save-dev eslint-plugin-react-hooks module.exports = { plugins: [ 'react-hooks',
], rules: { 'react-hooks/rules-of-hooks': 'error', 'react-hooks/exhaustive-deps': 'warn', } }
None
import React from 'react' import AnotherComponent from './AnotherComponent' function MyComponent({
id }) { const onClick = React.useCallback(() "=> { "// do something with id }, [id]) return ( <AnotherComponent onClick={onClick} "/> ) }
const onClick = React.useCallback(() "=> { "// do something with
id }, [id])
const onClick = React.useMemo(() "=> { return () "=> {
"// do something with id } }, [id])
import React from 'react' import AnotherComponent from './AnotherComponent' function MyComponent({
id }) { const onClick = React.useCallback(() "=> { "// do something with id }, [id]) return ( <AnotherComponent onClick={onClick} "/> ) }
Does AnotherComponent need reference equality?
import React from 'react' function AnotherComponent({ onClick }) { "//
expensive rendering } export default React.memo(AnotherComponent)
Pros • less typing, more thinking • reusing behavior is
nicer • no need for classes anymore…?
Cons • unlearning lifecycle methods • are there any more
cons? that’s up to you
Questions? @silvenon