自己写的勿喷：
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>don1</title>
<meta name="author" content="gy" />
<!-- Date: 2017-02-22 -->
<script src="jQuery1.11.1.js"></script>
<script type="text/javascript">
$(function() {
$("li").each(function() {
$(this).children().eq(1).focus(function() {
//alert($(this).children().eq(2));
$(this).next().css("background-color", "red");
}).blur(function() {
$(this).next().css("background-color", "");
});
});
});
//.css("background-color","red");
</script>
</head>
<body>
<ul>
<li>
<label>用户名:</label>
<input />
<p>
变色
</p>
</li>
<li>
<label>密码:</label>
<input />
<p>
变色
</p>
</li>
<li>
<label>等等:</label>
<input/>
<p>
变色
</p>
</li>
<li>
<label>等等:</label>
<input/>
<p>
变色
</p>
</li>
</ul>
</body>
</html>