<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>getElementByTagName的使用</title>
<style type="text/css">
.dd1 {
color: red;
}
.dd2 {
color: blue;
}
</style>
<script type="text/javascript">
function changeColor() {
var obj1, num, i;
obj1 = document.getElementById("s1").getElementsByTagName("a");
num = document.getElementById("s1").getElementsByTagName("a").length;
for (i = 0; i < num; i++) {
obj1[i].className = "dd2";
}
}
</script>
</head>
<body>
<div id="s1" onmouseover="changeColor()">
<a href="http://www.jb51.net/article/ddd" class="dd1">dfdfd</a> <a
href="http://www.jb51.net/article/ddd" class="dd1">dfdfd</a> <a
href="http://www.jb51.net/article/ddd" class="dd1">dfdfd</a>
</div>
</body>
</html>
原文：http://www.cnblogs.com/hhls/p/5657258.html