text: const Item = React.createClass({
      displayName: 'Item',
      getDefaultProps() {
          console.log('get defult props');
          return {
              group: 123
          }
      },
      getInitialState() {
          console.log('get initial state');
          return {
              name: 'leo'
          }
      },
      componentWillMount() {
          console.log('component will mount');
          this.state.name = 'liang';
      },
      componentDidMount() {
          console.log('component did mount');
          const dom = ReactDOM.findDOMNode(this);
          console.log(dom);
  
          let isYellow = false;
  
  
          setInterval(function () {
              if (isYellow) {
                  dom.style.backgroundColor = 'red';
                  isYellow = false;
              } else {
                  dom.style.backgroundColor = 'yellow';
                  isYellow = true;
              }
          }, 1000);
      },
      render() {
          console.log('render');
          return <div>{this.props.group + this.state.name}</div>
      }
  });
  
  ReactDOM.render(<div>
      <Item/>
  </div>, document.getElementById('test'));