<html><head><script src="https://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script><script>$(document).ready(function(){ $("button").click(function(){ $("p").html(function(n){ return "This p element has index: " + n; }); });});</script></head><body><button>Change the content of the p elements</button><p>This is a paragraph.</p><p>This is another paragraph.</p></body></html>