<html>
<head>
<script src="https://libs.baidu.com/jquery/1.10.2/jquery.min.js">
</script>
<script>
$(document).ready(function(){
$("button").click(function(){
var btn = $(this).text();
$("p").css("background-color","white");
$("p" + btn).css("background-color","yellow");
});
});
</script>
</head>
<body>
<button>:last</button>
<button>:last-child</button>
<button>:last-of-type</button><br>
<p>The first paragraph in body, and the first child in div.</p>
<div style="border:1px solid;">
<p>The first paragraph in div, and the first child in div.</p>
<p>The last paragraph in div, and the last child in div.</p>
</div><br>
<div style="border:1px solid;">
<span>This is a span element, and the first child in this div.</span>
<p>The first paragraph in another div, and the second child in this div.</p>
<p>The last paragraph in another div, and the third child in this div.</p>
<span>This is a span element, and the last child in this div.</span>
</div><br>
<div style="border:1px solid">
<p>The first paragraph in another div, and the first child in this div.</p>
<p>The last paragraph in the another div, and the last child in this div.</p>
</div>
<p>The last paragraph in body, and the last child in div.</p>
</body>
</html>