 <p>If it's just a single input, you can use <a href="https://developer.mozilla.org/en-US/docs/Web/API/window.prompt" rel="nofollow">the built-in prompt()</a> method.</p> <p>Otherwise, you would have to <a href="http://stackoverflow.com/questions/6265574/popup-form-using-html-javascript-css">pop up your own form</a>.</p>