<!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=utf-8" />
<title>无标题文档</title>
<style>
span{
height:300px;
300px;
background:#F00;
margin: 10px;
}
</style>
</head>
<body>
<div id='mydiv'>
<span id='span'>点击我变成蓝色</span>
<span id='span2'>点击我变成蓝色</span>
<span id='span3'>点击我变成蓝色</span>
<span id='span4'>点击我变成蓝色</span>
</div>
</body>
</html>
<script>
function $tag(tag,id){
var dom = document.getElementById(id);
return dom.getElementsByTagName(tag);
}
//缩小搜索范围
//先根据id 再根据tag
var spans = $tag('span','mydiv');
for(var i=0;i<spans.length;i++) {
spans[i].onclick = function(){
this.style.background= 'blue';
}
}
</script>