Drag and drop на HTML5

<div id="boxA"
  ondragenter="return dragEnter(event)"
  ondrop="return dragDrop(event)"
  ondragover="return dragOver(event)">

  <div id="drag" draggable="true"
  ondragstart="return dragStart(event)"
  ondragend="return dragEnd(event)">Тащи меня</div>

  <div id="drag2" draggable="true"
  ondragstart="return dragStart(event)"
  ondragend="return dragEnd(event)">Тащи меня </div>

  <div id="drag3" draggable="true"
  ondragstart="return dragStart(event)"
  ondragend="return dragEnd(event)">тащи меня</div>

  </div>

<div id="boxB"
  ondragenter="return dragEnter(event)"
  ondrop="return dragDrop(event)"
  ondragover="return dragOver(event)">
  </div>
<div id="boxC"
  ondragenter="return dragEnter(event)"
  ondrop="return dragDrop(event)"
  ondragover="return dragOver(event)">
  </div>

<style type="text/css">
#boxA, #boxB, #boxC {  
  float:left; width:165px; height:165px; padding:10px; margin:10px;  
}

#boxA { background-color: #474747; }
#boxB { background-color: #474747; }
#boxC { background-color: #474747; }

#drag, #drag2, #drag3 {
  width:30px; height:30px; padding:5px; margin:5px;
  -moz-user-select:none;
}
#drag { background-color: #e8e8e8;}
#drag2 { background-color: orange;}
#drag3 { background-color: purple; border:3px brown solid;}

</style>
<script type="text/javascript">
function dragStart(ev) {
  ev.dataTransfer.effectAllowed='move';
  //ev.dataTransfer.dropEffect='move';
  ev.dataTransfer.setData("Text", ev.target.getAttribute('id'));
  ev.dataTransfer.setDragImage(ev.target,0,0);
  return true;
}

function dragEnter(ev) {
  var idelt = ev.dataTransfer.getData("Text");
  return true;
}

function dragOver(ev) {
  var idelt = ev.dataTransfer.getData("Text");
  var id = ev.target.getAttribute('id');
  if( (id =='boxB' || id =='boxA') && (idelt == 'drag' || idelt=='drag2'))
  return false;
  else if( id =='boxC' && idelt == 'drag3')
  return false;
  else
  return true;
}

function dragEnd(ev) {
  ev.dataTransfer.clearData("Text");
  return true
}

function dragDrop(ev) {
  var idelt = ev.dataTransfer.getData("Text");
  ev.target.appendChild(document.getElementById(idelt));
  ev.stopPropagation();
  return false;  
}

</script>