React 錯誤Each child in an array or iterator should have a unique “key” prop

當你在寫react的時候報了類似於這樣子的錯：Each child in an array or iterator should have a unique “key” prop.

原因是這樣子的：React can’t know that your array is static, so you get the warning. The most practical thing to do here is to write something like.

解決辦法只要在循環的每個子項添加一個key就行了，代碼如下：

var names = [‘Alice’, ‘Emily’, ‘Kate’];

 

ReactDOM.render(

<div>

{

names.map(function (name, key) {

return <div key={key}>Hello, {name}!</div>

})

}

</div>,

document.getElementById(‘example’)

);