<html><head><script src="https://libs.baidu.com/jquery/2.1.4/jquery.min.js"></script><script>$(document).ready(function(){ $("button").click(function(){ $("p").prepend(function(n){ return "<b>This p element has index " + n + "</b>. "; }); });});</script></head><body><h1>This is a heading</h1><p>This is a paragraph.</p><p>This is another paragraph.</p><button>Insert content at the beginning of each p element</button></body></html>