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
setState ftw
Search
Michele Bertoli
October 06, 2017
Programming
12
3.6k
setState ftw
"Nobody knows how to do anything without Redux anymore. It's ridiculous." - @mjackson
Let's fix it!
Michele Bertoli
October 06, 2017
Tweet
Share
More Decks by Michele Bertoli
See All by Michele Bertoli
setState Machine
michelebertoli
10
1.8k
Test Like It's 2017
michelebertoli
3
870
Painless Testing
michelebertoli
2
180
Proper Error Handling
michelebertoli
10
1.7k
CSS in JS
michelebertoli
0
620
Inline Styles
michelebertoli
6
790
UNLEARN EVERYTHING
michelebertoli
5
1.7k
Other Decks in Programming
See All in Programming
Make Impossible States Impossibleを 意識してReactのPropsを設計しよう
ikumatadokoro
0
240
型付き API リクエストを実現するいくつかの手法とその選択 / Typed API Request
euxn23
8
2.2k
NSOutlineView何もわからん:( 前編 / I Don't Understand About NSOutlineView :( Pt. 1
usagimaru
0
340
Amazon Qを使ってIaCを触ろう!
maruto
0
410
アジャイルを支えるテストアーキテクチャ設計/Test Architecting for Agile
goyoki
9
3.3k
距離関数を極める! / SESSIONS 2024
gam0022
0
290
.NET のための通信フレームワーク MagicOnion 入門 / Introduction to MagicOnion
mayuki
1
1.7k
Jakarta EE meets AI
ivargrimstad
0
150
WebフロントエンドにおけるGraphQL(あるいはバックエンドのAPI)との向き合い方 / #241106_plk_frontend
izumin5210
4
1.4k
Generative AI Use Cases JP (略称:GenU)奮闘記
hideg
1
300
CSC509 Lecture 12
javiergs
PRO
0
160
as(型アサーション)を書く前にできること
marokanatani
10
2.7k
Featured
See All Featured
Scaling GitHub
holman
458
140k
ピンチをチャンスに:未来をつくるプロダクトロードマップ #pmconf2020
aki_iinuma
109
49k
Designing for humans not robots
tammielis
250
25k
The Straight Up "How To Draw Better" Workshop
denniskardys
232
140k
Git: the NoSQL Database
bkeepers
PRO
427
64k
The MySQL Ecosystem @ GitHub 2015
samlambert
250
12k
GraphQLとの向き合い方2022年版
quramy
43
13k
Principles of Awesome APIs and How to Build Them.
keavy
126
17k
The Success of Rails: Ensuring Growth for the Next 100 Years
eileencodes
44
6.8k
Teambox: Starting and Learning
jrom
133
8.8k
I Don’t Have Time: Getting Over the Fear to Launch Your Podcast
jcasabona
28
2k
KATA
mclloyd
29
14k
Transcript
setState ftw @MicheleBertoli
My name’s Michele and I’m a React fanboy since 2014
I work in Ads at Facebook, and I contribute to
a pretty sophisticated React UI
setState is the primary method you use to update the
UI in React
Are we really going to talk about setState for 40
minutes?
YES
Ok, why?
“I’m learning React but I don’t understand reducers.” Anonymous, Mar
2017
react
react-redux redux react react-router react-router-redux
react-redux redux react react-router react-router-redux
The community
“Nobody knows how to do anything without Redux anymore. It's
ridiculous.” @mjackson, Jun 2016
“3 Reasons why I stopped using React.setState.” @mweststrate, Jun 2016
“I love setState. In 3 1/2 years, I haven't needed
anything more.” @chantastic, Mar 2017
“You might not need Redux.” @dan_abramov, Sep 2016
Common Pitfalls
setState({ title: 'Here comes the sun' }) console.log(this.state.title)
setState is asynchronous
setState({ counter: this.state.counter + 1 }) setState({ counter: this.state.counter +
1 })
Object.assign( prevState, { counter: this.state.counter + 1 }, { counter:
this.state.counter + 1 }, )
Multiple setState calls get batched
this.state.title = 'Come together'
Mutating the state is an anti-pattern
this.state = { song: { title: 'Let it be', year:
1970, }, }
this.setState({ song: { title: 'Hey Jude', }, })
State changes are shallow merged
setState
yarn add setstate - DON’T TRY THIS AT HOME -
None
“If setState was packaged up as a lib, people would
love it.” @chantastic, Jul 2017
setState enqueues changes to the component state and tells React
that a component and its children need to be re-rendered with the updated state.
setState enqueues changes to the component state and tells React
that a component and its children need to be re-rendered with the updated state.
setState(updater, [callback])
(prevState, props) => stateChange
setState(stateChange, [callback])
Best practices
@dan_abramov, Jul 2016
this.state = { price: `${props.currency}${props.value}`, } Don’t
this.setState({ request: API.get(...), }) Don’t
Testing
this.setState( (prevState, props) => ({ counter: prevState.counter + props.step, })
)
export const increment = (prevState, props) => ({ counter: prevState.counter
+ props.step, })
import { increment } from './updaters' this.setState(increment)
test('increment', () => { const prevState = { counter: 1
} const props = { step: 1 } expect( increment(prevState, props) ).toEqual({ counter: 2 }) })
test('increment', () => { const prevState = { counter: 1
} const props = { step: 1 } expect( increment(prevState, props) ).toMatchSnapshot() })
Separation of concerns
• Container: data and behaviour • Presentational: appearance Container and
Presentational
componentDidMount() { API.get(...).then(s => this.setState(s)) } render() { return <Dumb
{...this.state} /> }
cb() { API.post(...).then(s => this.setState(s)) } render() { return <Dumb
{...this.state} cb={this.cb} /> }
yarn add react-fetching
<ReactFetching url="https://api.punkapi.com/v2/beers" ok={beers => <h1>{beers[0].name}</h1>} />
• Higher-order components • Component => Component • Options =>
Component => Component Composition
yarn add react-refetch
connect(mapPropsToRequests)(Component)
connect(() => ({ f: 'https://api.punkapi.com/v2/beers' }))( ({ f }) =>
f.fulfilled ? <h1>{f.value[0].name}</h1> : null )
Sharing state
Do you even lift (your state up)?
None
None
None
componentDidMount() { API.get(...).then(s => this.setState(s)) } render() { return <div>{this.state.data}</div>
}
componentDidMount() { API.get(...).then(this.props.cb) } render() { return <div>{this.props.data}</div> }
cb(data) { this.setState({ data }) } render() { return <Child
{...this.state} cb={this.cb} /> }
yarn add react-broadcast
<Broadcast channel="state" value={this.state} > {this.props.children} </Broadcast>
<Subscriber channel="state"> {state => ( <div>{state.data}</div> )} </Subscriber>
Time travel
yarn add --dev react-lumberjack
None
Lumberjack.back() Lumberjack.forward()
Functional
dispatch(action) { this.setState( prevState => reducer(prevState, action) ) }
yarn add t-redux
const reducer = buildReducer({ 'INCREMENT': state => ({ counter: state.counter
+ 1, }), }) const initialState = { counter: 0 }
const inc = () => dispatcher.dispatch({ type: 'INCREMENT', }) const
Button = ({ counter }) => ( <button onClick={inc}>{counter}</button> )
withState([reducer], initialState)(Button)
• Best practices • Testing • Separation of concerns •
Sharing state • Time Travel • Functional Recap
State Management
• Higher-order components • Immutability • Pure functions • Generators
• Observables Requirements
• Make informed decisions about your tools • Understand the
tradeoffs involved in each decision Choose wisely
• react-redux uses setState • mobx-react uses forceUpdate Know your
tools
Takeaways
Keep it simple
Lift your state up
Have fun!
Michele Bertoli Front End Engineer at Facebook Author of React
Design Patterns and Best Practices Follow me @MicheleBertoli