例如,当我们实现一个ListItem组件的时候,这个组件封装了一个li元素,那么我们不应该在li元素上直接设置key属性,因为没有意义,key是用来跟踪数组才有意义,于是我们在NumberList组件使用到ListItem组件的时候,在数组方法里面设置key属性才有意义。好,我们先来看一个错误设置key属性的版本: ...
Keys只用在有数组的上下文才有意义。 示例:key的错误用法 functionListItem(props) {constvalue = props.value;return(<likey={value.toString()}>{value}); }functionNumberList(props) {constnumbers = props.numbers;constlistItems = numbers.map(item=>// 这是错误的,这里应该设置上key<ListItemvalue={item...
“When children have keys, React uses the key to match children in the original tree with children in the subsequent tree.”--in-depth explanation about why keys are necessary 1const listItems = numbers.map((number) =>23{number}45); 生成组件数组时,如果元素本身有id,我们将id作为数组元素的...
复制 Each childina list should have aunique"key"prop. 1. 根据意思就可以得到渲染列表的每一个子元素都应该需要一个唯一的key值 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 复制 const List = () => {return({data.map((item) => (<ListItemname={item.name}key={item.id}></ListItem>...
For each item in a list, you should pass a string or a number that uniquely identifies that item among its siblings. 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 ...
列表操作常用操作包含以下方法: 1、list.append(obj):在列表末尾添加新的对象 2、list.count(obj):统计某个元素在列表中出现的次数 3、list.extend(seq):在列表末尾一次性追加另一个序列中的多个值...(用新列表扩展原来的列表) 4、list.index(obj):从列表中找出某个值第一个匹配项的索引位置 5、list.inser...
react-window - demo - React components for efficiently rendering large lists and tabular data virtua - demo - A zero-config, fast and small (~3kB) virtual list component for React, Vue and Solid. Overlay Display overlay / modal / alert / dialog / lightbox / popup react-aria-modal - A...
config(object /optional) define keys to work with, this is the core concept for Keys components and it works as below longPressTouch(array /optional) define list of keycode active for long press handling ( default :[37, 38, 39, 40]) ...
Keys themselves should be a unique number or string; so if a React Component is the only child with its key, then React will repurpose the DOM Element represented by that key in future calls to render().Let’s demonstrate this with a simple list of todos rendered with React:...
不过最后发现 fieldKey 和 key 本质上是同一个东西,因为在 antd#components#Form#FormList 中我发现: 3.2.6 感想 其实单单对比 Antd 3.x 以及 Antd 4.x 背后的表单, 我们已经可以得出一个有趣的结论:表单方案的性能问题本质是在解决各个表单项与项之间及与表单整体之间的通信问题。 这里 antd 4.x 利用...