JavaScript editor

Three files, run in a sandboxed frame in this tab. Nothing is sent anywhere, and the code stays in this browser.

Playground

HTML

<h1 id="title">Hello</h1>
<button id="go">Change it</button>

CSS

body { font-family: system-ui, sans-serif; }

h1 { color: #C2603C; }

JavaScript

const title = document.getElementById('title');

document.getElementById('go').addEventListener('click', () => {
  title.textContent = 'Changed at ' + new Date().toLocaleTimeString();
  console.log('clicked');
});