<!DOCTYPE html>
<html>
<title>W3.JS</title>
<script src="https://www.w3schools.com/lib/w3.js"></script>
<body>
<h2>Testing W3.JS in HTML</h2>
<p>Click the button to toggle elements with class="city".</p>
<p>
<button onclick="w3.toggleShow('.city')">Toggle Hide/Show</button>
</p>
<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>