title: What is the different ReactDOM.findDOMNode(this.refs.a) vs this.refs.a?
body: <p>If getting element object directly from this.refs then Why ReactDOM.findDOMNode?</p>
  
  <pre><code>var HelloMessage = React.createClass({
  click:function(){
    console.log(ReactDOM.findDOMNode(this.refs.a))
    console.log(ReactDOM.findDOMNode(this.refs.b))
    console.log(this.refs.a)
    console.log(this.refs.b)
  },
    render: function() {
      return &lt;div&gt;&lt;div onClick={this.click}&gt;click&lt;/div&gt;Hello {this.props.name}{this.props.no?&lt;div ref="a"&gt;{this.props.no}&lt;/div&gt;:&lt;div ref="b"&gt;&lt;/div&gt;}&lt;/div&gt;;
    }
  });
  
  ReactDOM.render(&lt;HelloMessage name="John" no={1}/&gt;, mountNode);
  </code></pre>