代码示例：（标识：event_ondragover）
<!DOCTYPE HTML>
<html>
<head>
<style>
#droptarget {
float: left;
width: 200px;
height: 35px;
margin: 55px;
margin-top: 155px;
padding: 10px;
border: 1px solid #aaaaaa;
}
</style>
</head>
<body>
<p ondragstart="dragStart(event)" draggable="true" id="dragtarget">把我拖进矩形！</p>
<div id="droptarget" ondrop="drop(event)" ondragover="allowDrop(event)">
</div>
<p style="clear:both;"><b>注释：</b>Internet Explorer 8 及更早版本或 Safari 5.1 及更早版本不支持 drag 事件。</p>
<p id="demo"></p>
<script>
function dragStart(event) {
event.dataTransfer.setData("Text", event.target.id);
}
function allowDrop(event) {
event.preventDefault();
document.getElementById("demo").innerHTML = "The p element is OVER the droptarget.";
event.target.style.border = "4px dotted green";
}
function drop(event) {
event.preventDefault();
var data = event.dataTransfer.getData("Text");
event.target.appendChild(document.getElementById(data));
document.getElementById("demo").innerHTML = "The p element was dropped.";
}
</script>
</body>
</html>
