在线运行代码 - 代码学院 www.codexy.cn

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>代码学院(codexy.cn)</title>
</head>
<body>

<p>改实例使用了 HTML DOM 向 h1 元素添加 "onmouseenter" 和 "onmouseleave" 事件。</p>
<h1 id="demo">Mouse over me</h1>
<script>
document.getElementById("demo").onmouseenter = function() {mouseEnter()};
document.getElementById("demo").onmouseleave = function() {mouseLeave()};
function mouseEnter() {
    document.getElementById("demo").style.color = "red";
}
function mouseLeave() {
    document.getElementById("demo").style.color = "black";
}
</script>

</body>
</html>

源代码

动行结果