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
useRefについて調べてみた
Search
Kazuki Shibata
September 04, 2019
Technology
1
160
useRefについて調べてみた
2019.09.04 React LT会の発表資料です。
https://informetis.connpass.com/event/142183/
Kazuki Shibata
September 04, 2019
Tweet
Share
More Decks by Kazuki Shibata
See All by Kazuki Shibata
microCMSでif文を作る
shibe97
1
1.1k
SvelteKitでJamstackを試す
shibe97
1
1.1k
フロントエンドのトレンド〜サーバーレスSPA、Jamstack〜
shibe97
16
4.9k
Jamstack × PWA におけるキャッシュ戦略
shibe97
3
1.2k
CSR / SSR / SSGの動向2020
shibe97
2
1.6k
Jamstack×microCMS 実装編
shibe97
4
950
SentryでSPAのエラーログを収集する
shibe97
1
1.7k
フロントエンドエンジニアのキャリアパス
shibe97
9
3.8k
Containerどこに置く?
shibe97
1
1.9k
Other Decks in Technology
See All in Technology
第9回情シス転職ミートアップ_テックタッチ株式会社
forester3003
0
130
白金鉱業Meetup_Vol.19_PoCはデモで語れ!顧客の本音とインサイトを引き出すソリューション構築
brainpadpr
2
470
Windows 11 で AWS Documentation MCP Server 接続実践/practical-aws-documentation-mcp-server-connection-on-windows-11
emiki
0
670
VISITS_AIIoTビジネス共創ラボ登壇資料.pdf
iotcomjpadmin
0
140
キャディでのApache Iceberg, Trino採用事例 -Apache Iceberg and Trino Usecase in CADDi--
caddi_eng
0
170
2年でここまで成長!AWSで育てたAI Slack botの軌跡
iwamot
PRO
2
140
ObsidianをMCP連携させてみる
ttnyt8701
2
140
Agentic Workflowという選択肢を考える
tkikuchi1002
1
350
JSX - 歴史を振り返り、⾯⽩がって、エモくなろう
pal4de
3
1.1k
TerraformをSaaSで使うとAzureの運用がこんなに楽ちん!HCP Terraformって何?
mnakabayashi
0
300
Workflows から Agents へ ~ 生成 AI アプリの成長過程とアプローチ~
belongadmin
3
170
米国国防総省のDevSecOpsライフサイクルをAWSのセキュリティサービスとOSSで実現
syoshie
2
780
Featured
See All Featured
What's in a price? How to price your products and services
michaelherold
245
12k
Designing Experiences People Love
moore
142
24k
Thoughts on Productivity
jonyablonski
69
4.7k
StorybookのUI Testing Handbookを読んだ
zakiyama
30
5.8k
The Invisible Side of Design
smashingmag
299
51k
CSS Pre-Processors: Stylus, Less & Sass
bermonpainter
357
30k
GraphQLの誤解/rethinking-graphql
sonatard
71
11k
The World Runs on Bad Software
bkeepers
PRO
68
11k
VelocityConf: Rendering Performance Case Studies
addyosmani
330
24k
Done Done
chrislema
184
16k
Gamification - CAS2011
davidbonilla
81
5.3k
How to Think Like a Performance Engineer
csswizardry
24
1.7k
Transcript
useRefʹ͍ͭͯௐͯΈͨ @shibe97 2019.9.4 React LTձ
ࣲా ف ΥϯλגࣜձࣾͰmicroCMSͱ͍͏ϔουϨεCMSΛ ࡞͍ͬͯ·͢ɻ ීஈReact͍Ͱɺ࠷ۙVueͪΐͬͱ৮Γ·͢ɻ @shibe97
None
ೖྗϑΥʔϜͱAPIΛඵͰ࡞Ͱ͖ΔαʔϏε
React Hooksͱ • React 16.8͔ΒՃ͞Εͨػೳ • Functional ComponentʹClass Componentͱಉ༷ͷॲཧ͕ Ͱ͖ΔΑ͏ʹՃ͞Εͨ
• stateϥΠϑαΠΫϧ૬ͷͷ
useRefͱ • DOMͷࢀরʹ͑Δ • ࠶ඳըͤ͞ͳ͍มཧ͕Ͱ͖Δ
DOMͷࢀরʹ͑ΔʢެࣜྫΑΓʣ function TextInputWithFocusButton() { const inputEl = useRef(null); const onButtonClick
= () => { // `current` points to the mounted text input element inputEl.current.focus(); }; return ( <> <input ref={inputEl} type="text" /> <button onClick={onButtonClick}>Focus the input</button> </> ); }
࠶ඳըͤ͞ͳ͍มཧ͕Ͱ͖Δ • refΦϒδΣΫτΛcurrentϓϩύςΟʹอ࣋͢Δ • ࠶ඳը࣌ɺຖճಉ͡refΦϒδΣΫτΛฦ͢ • currentʹೖͯ͠࠶ඳը͞Εͳ͍ { current: initialValue
}
useRefͷ࣮ function mountRef<T>(initialValue: T): {current: T} { const hook =
mountWorkInProgressHook(); const ref = {current: initialValue}; if (__DEV__) { Object.seal(ref); } hook.memoizedState = ref; return ref; } function updateRef<T>(initialValue: T): {current: T} { const hook = updateWorkInProgressHook(); return hook.memoizedState; } ϝϞϦ্ͷΛຖճฦ͚ͩ͢ ϝϞϦ্ͰΦϒδΣΫτΛอ࣋ currentϓϩύςΟʹΛอ࣋
͜ͷΈΛར༻Ͱ͖ΔྫͬͯͳΜͩΖ͏
DOMͩʂ
inputཁૉͷྫ: useState function TextInput() { const [ text, setText ]
= useState(‘’); const onChange = useCallback(e => { setText(e.target.value); }; return ( <input onChange={onChange} type="text" /> ); } ςΩετΛมߋ͢Δͨͼʹඳը͞ΕΔ
inputཁૉͷྫ: useRefʢcurrentࢦఆʣ function TextInput() { const { current } =
useRef(null); const onChange = useCallback(e => { current = e.target.value; }); return ( <input onChange={onChange} type="text" /> ); } ςΩετΛมߋͯ͠࠶ඳը͞Εͳ͍
͋ΕɺͰ͜Εͬͯɾɾɾ
inputཁૉͷྫ: useRefʢDOMࢀরʣ function TextInput() { const inputEl = useRef(null); return
( <input ref={inputEl} type="text" /> ); } ͪΖΜ͜ͷํ๏࠶ඳը͞Εͳ͍
·ͱΊ • useRefΛอ࣋Ͱ͖Δ্ʹɺมߋͯ͠࠶ඳը͞Εͳ͍ • inputཁૉʹuseStateΑΓuseRefͷํ͕ύϑΥʔϚϯεྑ͍ • ͪΖΜControlled Componentʹ͍ͨ͠߹useStateʹ͢Δ ඞཁ͋Γ
͓·͚
useRefΦϒδΣΫτΛࢀর͍ͯ͠Δ͔Β ෦ϓϩύςΟมߋͨ͠ͱ͜ΖͰ࠶ඳը͞Εͳ͍ΜͩΖ͏
Α͠ɺLTωλ͜ΕͰ͍͜͏ʂ
useRefͷ࣮ function mountRef<T>(initialValue: T): {current: T} { const hook =
mountWorkInProgressHook(); const ref = {current: initialValue}; if (__DEV__) { Object.seal(ref); } hook.memoizedState = ref; return ref; } function updateRef<T>(initialValue: T): {current: T} { const hook = updateWorkInProgressHook(); return hook.memoizedState; } ϝϞϦ্ͷΛຖճฦ͚ͩ͢ ϝϞϦ্ͰΦϒδΣΫτΛอ࣋ currentϓϩύςΟʹΛอ࣋
·ͬͨؔ͘ͳ͔ͬͨ
Thanks :) @shibe97