componentDidMount没有更新我的状态吗？

Question

我是一个新的反应，我只是做了一个视图计数器的各种divs.For，我需要的高度的div和scrollTop的height.But后，我必须设置的值，它不工作的values.But。

var React = require('react');
var ReactDOM = require('react-dom');
var NewsDetail = require('./news-details');
var $ = require('jquery');
module.exports = React.createClass({
      getInitialState: function() {
        return {
          news: [{
            id: "5",
            data: "I probably am using the wrong I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value terminology here but this is what I'm trying to do. I want to create a map with a value for each key and a value for each key's object. S"
          }, {
            id: "6",
            data: "I probably am using the wrong I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value terminology here but this is what I'm trying to do. I want to create a map with a value for each key and a value for each key's object. S"
          }, {
            id: "7",
            data: "I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value for each key and a value for each key's object. S"
          }, {
            id: "8",
            data: "I probably am using the wrong I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value terminology here but this is what I'm trying to do. I want to create a map with a value for each key and a value for each key's object. S"
          }, {
            id: "9",
            data: "I probably am using the wrong I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value I probably am using the wrong terminology here but this is what I'm trying to do. I want to create a map with a value terminology here but this is what I'm trying to do. I want to create a map with a value for each key and a value for each key's object. S"
          }, ],
          length: null,
          height: 0
        }
      },
      componentWillMount: function() {},
      componentDidMount: function() {

        console.log(this.state.length)
        var lengthh = document.getElementById('newscontanier').children.length;
        console.log(lengthh);
        if(lengthh != this.state.length) {
          this.setState({
            length: lengthh //Still  null
          })
        }
      },
      render: function() {
        var newsdata = this.state.news.map(function(newss) {
            return( < NewsDetail key = {
                newss.id
              } {...newss
              }
              />)
            });
          return(<div className="newscontanier" id="newscontanier">{newsdata}</div>)
        }
      })

Answer 1

这里只有一个语法错误，删除jsx -

 return (
    <div className="newscontanier" id="newscontanier">{newsdata}</div>
 );

请参阅此处的工作副本- https://jsfiddle.net/69z2wepo/54531/