react Warning: Each child in an array or iterator should have a unique "key" prop. Check the render

出现错误情况：Warning: Each child in an array or iterator should have a unique "key" prop. Check the render method of `SubParent`. See https://fb.me/react-warning-keys for more information.

说明在遍历数组的时候，没有指定key，解决方法：

加上key属性，并赋值，如    

<tr key={tweet.id}>

render:function(){
var listItems = this.state.tweets.map(function(tweet, index) {
return (
<tr key={tweet.id}>
<td>{tweet.id}{index}</td>
<td>{tweet.pname}</td>
<td>{tweet.name}</td>
<td><a  href="#" >修改</a></td>
</tr>

);
});

}