代码示例：（标识：event_ondragover_addeventlistener）
<!DOCTYPE HTML>
<html>
<head>
<style>
#droptarget {
float: left;
width: 200px;
height: 45px;
margin: 55px;
margin-top: 155px;
padding: 10px;
border: 1px solid #aaaaaa;
}
</style>
</head>
<body>
<p>本例使用 addEventListener() 方法将 "dragstart" 和 "drag" 事件附加到 p 元素，并将 "dragover" 和 "drop" 事件附加到 div 元素。</p>
<p draggable="true" id="dragtarget">把我拖进矩形！</p>
<div id="droptarget"></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>
var drag = document.getElementById("dragtarget");
var drop = document.getElementById("droptarget");
/* 在拖动目标上触发的事件 */
drag.addEventListener("dragstart", function(event) {
event.dataTransfer.setData("Text", event.target.id);
});
drag.addEventListener("drag", function(event) {
document.getElementById("demo").innerHTML = "The p element is being dragged.";
});
/* 在放置目标上触发的事件 */
drop.addEventListener("dragover", function(event) {
event.preventDefault();
document.getElementById("demo").innerHTML = "The p element is OVER the droptarget.";
event.target.style.border = "4px dotted purple";
});
drop.addEventListener("drop", function(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>
