{float:left; width:100px; height:35px; margin:10px;padding:10px;border:1px solid #aaaaaa;}
<script type="text/javascript">
ev.dataTransfer.setData("Text",ev.target.id);
var data=ev.dataTransfer.getData("Text");
ev.target.appendChild(document.getElementById(data));
<div id="div1" ondrop="drop(event)" ondragover="allowDrop(event)">
<img src="/img/eg_banner_W3xue100_35.gif" draggable="true" ondragstart="drag(event)" id="drag1" />
<div id="div2" ondrop="drop(event)" ondragover="allowDrop(event)"></div>