title: Missing ref node on resize event
body: <p>i'm try to call "setHolePosition" method on resize event, but this.hole is empty, but first time it works ok. when i'm resize window, console.log show empty array, i can't understand why ? And where i can store refs in react App</p>
  
  <pre><code>import React, {Component} from 'react';
  import $ from 'jquery';
  
  import './indexPageStyles.sass';
  
  class IndexPageComponent extends Component {
    showHole() {
      setTimeout(() =&gt; {
        this.hole.addClass('hole--visible');
        this.setHolePosition();
      }, 1000)
    }
    setHolePosition(){
  
      const doc = $(document);
      let dh = doc.height();
      let dw = doc.width();
  
      console.log(this.hole);
  
      this.hole.css({
        top: dh / 2 - $(this.hole).height() / 2,
        left: dw / 2 - $(this.hole).width() / 2
      });
  
  
      // TODO: unbind this listener
      window.addEventListener('resize', this.setHolePosition);
    }
  
    render() {
      return (
        &lt;div className="indexPage"&gt;
          &lt;div className="hole" ref={(hole) =&gt; {
            this.hole = $(hole);
            this.showHole();
          }}&gt;&lt;/div&gt;
        &lt;/div&gt;
      )
    }
  }
  
  export default IndexPageComponent;
  </code></pre>