import{useQuery}from'@tanstack/react-query';constfetchTodos=async():Promise<Todo[]>=>{constresponse=awaitfetch('api/tasks');if(!response.ok){thrownewResponseError('Failed to fetch todos',response);}returnawaitresponse.json();};exportconstuseTodos=():UseTodos=>{const{data:todos=[],isLoadin...
export default function App() { const [count, setCount] = useState(0); useEffect(() => { setCount(count + 1); }, []); return {count}; } 具体再解释一下 useEffect 使用的 4 种情况: 「第二个参数不传」:任何状态更新,都会触发 useEffect的副作用函数。 useEffect(() => { setCount(co...
AI代码解释 // App.jsimport{useEffect,useRef}from'react';exportdefaultfunctionApp(){constrefContainer=useRef(null);useEffect(()=>{// 👇️ this is reference to input elementconsole.log(refContainer.current);refContainer.current.focus();},[]);return();} useRef()钩子可以被传递一个初始值作为...
classWelcomeextendsReact.Component{render(){returnhello,{this.props.name}} }functionApp(){return(<Welcomename="Sara"/><Welcomenmae="Peng"/>); }export{Welcome,App}; index.js import{App}from'./components/Com';constelement=<App/>;ReactDOM.render(element,document.getElementById('root'));...
import { useState } from 'react'; function MyButton() { const [count, setCount] = useState(0); function handleClick() { setCount(count + 1); } return ( Clicked {count} times ); } export default function MyApp() { return ( Counters that update separately <MyButton /> <MyButto...
当我们尝试使用默认导出来导出一个匿名函数时,会导致"Unexpected default export of anonymous function"警告。为了解决该错误,在导出函数之前,为函数赋予一个名称。 这里有个例子来展示警告是如何发生的。 // Header.js// 👇️ default export for anonymous function// ⛔️ Unexpected default export of anon...
export default function Methods() { const btn = (e)=>{ console.log('点你了...'); //自带event 事件对象 console.log(e); //阻止事件冒泡 e.stopPropagation() } return ( 点我呀 ) } 绑定事件并传递参数 如果直接绑定事件,react
export default function App() { let [opacity, setOpacity] = useState(1); const [count, setCount] = useState(0); //初始化的时候添加一个定时器 useEffect(() => { const opacityTimer = setInterval(() => { opacity -= 0.1; if (opacity <= 0) { opacity = 1; ...
exportdefaultfunctionApp(){const[ value ,setInputValue ] =React.useState('')const[ isTransition , setTransion ] =React.useState(false)const[ query ,setSearchQuery ] =React.useState('')consthandleChange= (e) => {/* 高优先级任务 —— 改变搜索条件 */setInputValue(e.target.value)if(isTra...
// App.tsxexportconstContext=React.createContext({});exportdefaultfunctionApp() {// 在最外层执行 hooksconstmyHookResult =useMyHook();// 通过 Context 向下传递return(<Context.Providervalue={myHookResult}>{children}</ContextProvider>) }