1<!DOCTYPE html>
2<html>
3<head>
4<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
5<script>
6$(document).ready(function(){
7 $("button").click(function(){
8 $("h1, h2, p").addClass("blue");
9 $("div").addClass("important");
10 });
11});
12</script>
13<style>
14.important {
15 font-weight: bold;
16 font-size: xx-large;
17}
18
19.blue {
20 color: blue;
21}
22</style>
23</head>
24<body>
25
26<h1>Heading 1</h1>
27<h2>Heading 2</h2>
28
29<p>This is a paragraph.</p>
30<p>This is another paragraph.</p>
31
32<div>This is some important text!</div><br>
33
34<button>Add classes to elements</button>
35
36</body>
37</html>
38