title: how to get data from DataTransfer.getData in event Dragover or Dragenter
body: <p>i have a code : </p>
  
  <pre><code>element.addEventListener('dragstart',function(e){
     e.dataTransfer.setData('Text', 'something is here');
  },false);
  </code></pre>
  
  <p>when i getdata from DataTransfer.getData in event Drop is running.
  but when i want get data in event dragover or dragenter, data is null.</p>
  
  <pre><code>element.addEventListener('dragover',function(e){
     var a = e.dataTransfer.getData('Text');
     console.log(a);
  },false);
  </code></pre>
  
  <p>So, how to get data in event dragover or dragenter</p>