sargonco

<!DOCTYPE html>
<html>
<title>W3.JS</title>
<style>
.marked {
background-color: orange;
font-size: 30px;
color: white;
}
</style>
<script src="/lib/w3.js"></script>
<body>

<p>Click the button to toggle the "marked" class of id="London".</p>

<button onclick="w3.toggleClass('#London','marked')">Toggle Class</button>

<div id="London" class="city">
<h2>London</h2>
<p>London is the capital city of England.</p>
</div>

<div id="Paris" class="city">
<h2>Paris</h2>
<p>Paris is the capital of France.</p>
</div>

<div id="Tokyo" class="city">
<h2>Tokyo</h2>
<p>Tokyo is the capital of Japan.</p>
</div>

</body>
</html>

Click the button to toggle the "marked" class of id="London".

London

London is the capital city of England.

Paris

Paris is the capital of France.

Tokyo

Tokyo is the capital of Japan.