<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><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>