| 海外TECH |
MakeUseOf |
How to Draw on the Desktop on Windows 10 & 11 |
https://www.makeuseof.com/draw-on-windows-11-10-desktop/
|
windows |
2023-01-28 20:15:16 |
| 海外TECH |
DEV Community |
useRef() 🪝 |
https://dev.to/mihir_chhatre/useref-5pf
|
useRef 🪝useRef is similar to useSate as it allows us to persist remain unchanged values between renders but unlike useState the Ref hook does not cause a re render when the mutable value is changed useRef returns a mutable object whose current property is set with an initial value that is passed as an argument to the Ref function const refObject useRef initial value In the above example refObject is the returned object This object has a current property that can be used to obtain the value of the referenced object at any time There are two primary uses of useRef To create persisted mutable variables these are called refs or references To access DOM elements or React elements Let s dive into these useRef to create persisted mutable variablesTrying to count the number of times a component re renders using useState will lead to an infinite loop as useState itself causes a re render This is demonstrated in the example below import React useState useEffect from react function App const text setText useState const count setCount useState useEffect gt setCount prevStateCount gt prevStateCount return lt div gt lt input value text onChange e gt setText e target value gt lt div gt Type some text in the box lt div gt lt div gt Component rendered count times lt div gt lt div gt export default AppDuring initial component render the count is incremented which causes the component to re render and hence the count increments again leading to re rendering the component Essentially this is an infinite loop of incrementing count and component re rendering Refs to the rescue 🛟 Refs can be used to solve the infinite loop issue that arises due to re rendering when using the state hook import React useState useEffect useRef from react function App const text setText useState const count useRef useEffect gt count current count current return lt div gt lt input value text onChange e gt setText e target value gt lt div gt Type some text in the box lt div gt lt div gt Component rendered count current times lt div gt lt div gt export default AppuseRef replaces useState and count is an object with a current property The current property persists as it is updated between different renders We can observe from the image below each time a character is entered in the input field the count increments Since apple is entered the count is incremented times on initial render increment by for each character Irrespective of the number of times the count changes our component is not re rendered since it is decoupled from our component render cycle Accessing DOM elementsA more common use for Refs is when we need to reference HTML elements Every HTML element has a ref attribute We can add the ref attribute to the element to access the element directly in the DOM Let s understand this use case with an example Consider the code for a scenario where we want to focus on an input when a button is clicked import React useRef from react function App const inputRef useRef const focus gt inputRef current focus return lt div gt lt input ref inputRef gt lt button onClick focus gt Click to focus lt button gt lt div gt export default AppEach time inputRef is rendered on the screen the inputRef variable is set to the input element Therefore in the focus function we are accessing inputRef variable s current property this corresponds to input element and then focussing on it From the screenshot attached below we can observe how clicking on the button focuses on the input Another hack with useRef gt Imagine updating the state with every character when dealing with forms This could be slightly excessive Using Refs we can set up a connection between the HTML element that is rendered eventually and other JavaScript code Congratulations amp great going You have now covered three React hooks This would be a good point to re collect your understanding of these hooks If you feel confident dive straight into Part where I cover useReducer |
2023-01-28 20:24:31 |
| 海外科学 |
NYT > Science |
As the Colorado River Shrinks, Washington Prepares to Spread the Pain |
https://www.nytimes.com/2023/01/27/climate/colorado-river-biden-cuts.html
|
As the Colorado River Shrinks Washington Prepares to Spread the PainThe seven states that rely on the river for water are not expected to reach a deal on cuts It appears the Biden administration will have to impose reductions |
2023-01-28 20:39:56 |
| ニュース |
BBC News - Home |
Clare Drakeford: Wife of Wales' FM Mark Drakeford dies suddenly |
https://www.bbc.co.uk/news/uk-wales-64439545?at_medium=RSS&at_campaign=KARANGA
|
drakeford |
2023-01-28 20:02:04 |
| ニュース |
BBC News - Home |
Jerusalem shooting: Israeli PM warns of 'swift' response after attacks |
https://www.bbc.co.uk/news/world-middle-east-64438905?at_medium=RSS&at_campaign=KARANGA
|
attacks |
2023-01-28 20:52:45 |
| ニュース |
BBC News - Home |
Preston North End 0-3 Tottenham Hotspur: Son Heung-min and Arnaut Danjuma see Spurs through |
https://www.bbc.co.uk/sport/football/64438694?at_medium=RSS&at_campaign=KARANGA
|
Preston North End Tottenham Hotspur Son Heung min and Arnaut Danjuma see Spurs throughTwo excellent Son Heung min strikes and a debut goal for Arnaut Danjuma see Tottenham beat Preston to progress to the FA Cup fifth round |
2023-01-28 20:45:10 |
| ビジネス |
ダイヤモンド・オンライン - 新着記事 |
駆け込み相続・贈与の準備に！複雑な関係や手続きをスッキリ整理「書き込みシート」【PDF配布】 - 相続＆生前贈与 65年ぶり大改正 |
https://diamond.jp/articles/-/316377
|
書き込み |
2023-01-29 05:25:00 |
| ビジネス |
ダイヤモンド・オンライン - 新着記事 |
遺言書の「正しい書き方」とは？家族を不幸にしない争族防止の切り札 - 相続＆生前贈与 65年ぶり大改正 |
https://diamond.jp/articles/-/316376
|
生前贈与 |
2023-01-29 05:20:00 |
| ビジネス |
ダイヤモンド・オンライン - 新着記事 |
東京都の有料老人ホームランキング！中価格帯の介護型ベスト109【2023年版】 - 最適な介護施設選び＆老人ホームランキング |
https://diamond.jp/articles/-/316620
|
介護施設 |
2023-01-29 05:15:00 |
| ビジネス |
ダイヤモンド・オンライン - 新着記事 |
訪問介護は崩壊寸前！低賃金・高齢化でホームヘルパーは「絶滅危惧種」に - 最適な介護施設選び＆老人ホームランキング |
https://diamond.jp/articles/-/316619
|
介護施設 |
2023-01-29 05:10:00 |
| ビジネス |
ダイヤモンド・オンライン - 新着記事 |
外資系コンサルでも通用する論理力は「現代文の学び直し」で身に着く！鍵は思考法 - 仕事に効く！独学バイブル |
https://diamond.jp/articles/-/315362
|
外資系コンサルでも通用する論理力は「現代文の学び直し」で身に着く鍵は思考法仕事に効く独学バイブル現代は既存のビジネススキルがにわかに陳腐化し、すぐに新たなスキル習得を求められる大激変期です。 |
2023-01-29 05:05:00 |
| ビジネス |
東洋経済オンライン |
新卒でないと入りにくいが､勤続年は長い128社 トップの日本航空は新卒採用占有率が100% | CSR企業総覧 | 東洋経済オンライン |
https://toyokeizai.net/articles/-/648668?utm_source=rss&utm_medium=http&utm_campaign=link_back
|
新卒採用 |
2023-01-29 05:40:00 |
| ビジネス |
東洋経済オンライン |
科学調査で判明､｢ストーカー予備軍｣5つの要因 博多ストーカー殺人事件の容疑者は多くが合致 | 災害･事件･裁判 | 東洋経済オンライン |
https://toyokeizai.net/articles/-/648816?utm_source=rss&utm_medium=http&utm_campaign=link_back
|
博多駅前 |
2023-01-29 05:20:00 |
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