当拖动的元素位于目标上方时，JavaScript中哪个事件发生？
当拖动的元素位于放置目标上方时，会触发ondragover事件。
示例
您可以尝试运行以下代码以了解如何在JavaScript中实现ondragover事件-
<!DOCTYPE HTML>
<html>
<head>
<style>
.drag {
float: left;
width: 100px;
height: 35px;
border: 2px dashed #876587;
margin: 15px;
padding: 10px;
}
</style>
</head>
<body>
<div class="drag" ondrop="drop(event)" ondragover="dropNow(event)">
<p ondragstart="dragStart(event)" ondragend="dragEnd(event)" draggable="true" id="dragtarget">Drag!</p>
</div>
<div class="drag" ondrop="drop(event)" ondragover="dropNow(event)"></div>
<div id="box"></div>
<p>Drag the left box to the right or drag the right box to the left.</p>
<script>
function dragStart(event) {
event.dataTransfer.setData("Text", event.target.id);
}
function dropNow(event) {
event.preventDefault();
}
function dragEnd(event) {
document.getElementById("box").innerHTML = "拖完了！";
}
function drop(event) {
event.preventDefault();
var data = event.dataTransfer.getData("Text");
event.target.appendChild(document.getElementById(data));
document.getElementById("box").innerHTML = "元素成功删除！";
}
</script>
</body>
</html>