const [data, setData]=useState(list); const deleteFirstHanlde= () =>{ const newdata=JSON.parse(JSON.stringify(data)); newdata.shift(); setData(newdata); };return({data.map((item, index)=>({item.name} ))} 删除第一项 ); }; exportdefaultTestComp; 一、如果只是单纯的展示,不做任何...
first second 有了key 之后,React 就会知道带有'3'key 值的是新元素,而带有'1'和'2'的元素仅仅是移动了,不需要重新创建。 我们再来验证一下: constList=()=>{const[list,setList]=useState(data);return({list.map((item,idx)=>(<ListItemname={item.name}key={item.id}></ListItem>))}{setList([...
在这里可以使用列表的id属性作为key值以解决上面这个警告 const List = () =>{return({data.map((item)=>(<ListItem name={item.name} key={item.id}></ListItem>))}); }; 二、作用 跟Vue一样,React也存在diff算法,而元素key属性的作用是用于判断元素是新创建的还是被移动的元素,从而减少不必要的Diff ...
AI代码解释 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=...
()=>{constfetchData=async()=>{constresult=awaitaxios('https://hn.algolia.com/api/v1/search?query=redux',);setData(result.data);};fetchData();},[]);return({data.hits.map(item=>({item.title}))});}exportdefaultApp; 上面例子中,useState()用来生成一个状态变量(data),保存获取的数据...
{ data: user } = useQuery<User | null>([QUERY_KEY.user],async (): Promise<User | null> => getUser(user),{refetchOnMount: false,refetchOnWindowFocus: false,refetchOnReconnect: false,initialData: userLocalStorage.getUser,onError: () => {userLocalStorage.removeUser();}});useEffect((...
Usually, a key should be coming from your data, such as a database ID. React will rely on your keys to understand what happened if you later insert, delete, or reorder the items. App.js Download Reset Fork const products = [ { title: 'Cabbage', isFruit: false, id: 1 }, { ...
* */constnames = ['jQuery','zepto','angular','react','vue']// 1、创建虚拟DOM// li 标签一定要带 key属性,而且还不能一样 否则警告constul = ({names.map(name=> <likey={name}>{name})}) //2、渲染虚拟DOM ReactDOM.render(ul,
console.log(response.data.data.yesterday); 代码语言:javascript 代码运行次数:0 运行 AI代码解释 console.log(response.data.data.forecast); 2:空数组接收数据 在this.state里面写一个list:[]空数接收数据。 代码语言:javascript 代码运行次数:0 运行 ...
label}</Text> </TouchableOpacity> </ScaleDecorator> ); }; return ( <DraggableFlatList data={data} onDragEnd={({ data }) => setData(data)} keyExtractor={(item) => item.key} renderItem={renderItem} /> ); } const styles = StyleSheet.create({ rowItem: { height: 100, width: 100, ...