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<html><title>W3.JS</title><script src="https://www.w3schools.com/lib/w3.js"></script><body><p>Click the button to hide all p elements with class="intro".</p><button onclick="w3.hide('p.intro')">Hide</button><h2 class="intro">This is a heading with class="intro"</h2><p class="intro">This is a paragraph with class="intro".</p><p class="intro">This is also a paragraph with class="intro".</p><p>This is another paragraph.</p></body></html>