Keys值帮助React确定哪些组件已经改变了,增加了或者被移除了。 constnumbers =[1,2,3,4,5];constlistItems = numbers.map(item=><likey={item.toString()}>{item}); 数组中的每个组件都需要有一个确定的keys值,即一个确定的身份。 keys值最好是用字符串来做唯一标识符。我们通常用数据的ID来做主键。 Key...
}constnumbers = [1,2,3,4,5];ReactDOM.render(<NumberListnumbers={numbers}/>,document.getElementById('root') ); 一个很好的经验法则是map()调用中的元素需要键。 2. Keys在同级元素中是唯一的 (Keys Must Only Be Unique Among Siblings) 数组中使用的Keys在其兄弟之间应该是唯一的。 然而,它们不需...
ReactDOM.render( <NumberList numbers={numbers} />, document.getElementById('root') ); 当您运行此代码时,将会收到一条警告,Each child in an array or iterator should have a unique "key" prop. Check the render method of "NumberList". 提示指出应该为列表的每一项提供一个属性key。“key”是创...
ReactDOM.render(<NumberList numbers={numbers} />, document.getElementById('root')); // If you want your app to work offline and load faster, you can change // unregister() to register() below. Note this comes with some pitfalls. // Learn more about service workers: https:///CRA-PW...
键(Keys) 上面的例子中出现的警告告诉我们数组中的每一个元素都需要一个“key”(键)来进行标识。键(Keys) 帮助 React 标识哪个项被修改、添加或者移除了。有点类似于元素的唯一标识,相信会比较好理解。 挑选key 最好的方式是使用一个在它的同辈元素中不重复的标识字符串。多数情况你可以使用数据中的 IDs 作为...
This special key prop allows React internally to keep track of each element in the array of JSX, so that in case any of the elements are added, updated or deleted, React can optimize performance and keep track internally of those changes. The key should be a unique value associated with ...
React: Implementing Keys In Lists May 11, 2020 React Mapped arrays in React require each item to have a unique hey. This post covers why and how to implement them. Table of Contents Series Mapping The Array Adding Unique ID Optional: Adding Alt Tags Destructuring Properties ...
Quiz on ReactJS Lists - Learn how to work with lists in ReactJS, including rendering, keys, and list components. Master the essentials of managing lists in your React applications.
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键(Keys) 是React列表中非常重要的一个属性,它可以帮助 React 标识哪个项被修改、添加或者移除了,从而来进行重新渲染。数组中的每一个元素都应该有一个唯一不变的键(Keys)来标识。注:key值最好为同辈元素中不重复的表示字符串。多数情况下是用数据中的ID或者若没有id,则以map时的index作为key值。