title: React DnD: Avoid using findDOMNode
body: <p>I don't fully understand it but apparently <a href="https://github.com/yannickcr/eslint-plugin-react/issues/678#issue-165177220" rel="noreferrer">it isn't recommended to use findDOMNode()</a>.</p>
  
  <p>I'm trying to create drag and drop component but I'm not sure how I should access refs from the component variable. This is an example of what I currently have:</p>
  
  <pre><code>const cardTarget = {
      hover(props, monitor, component) {
          ...
          // Determine rectangle on screen
          const hoverBoundingRect = findDOMNode(component).getBoundingClientRect();
          ...
      }
  }
  </code></pre>
  
  <p><a href="https://github.com/gaearon/react-dnd/blob/master/examples/04%20Sortable/Simple/Card.js" rel="noreferrer">Source</a></p>
  
  <p><strong>Edit</strong></p>
  
  <p>It might be caused by my component being both the drag and drop source and target as I can get it to work in <a href="https://jsfiddle.net/hx7eutm1/2/" rel="noreferrer">this example</a> but not <a href="https://jsfiddle.net/h4w4btz9/1/" rel="noreferrer">this one</a>.</p>