Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p>Click the button to create a DIALOG element with some text.</p>

<button onclick="myFunction()">Try it</button>

<p><b>Note:</b> The dialog element is only supported in Chrome 37+, Safari 6+ and Opera 24+.</p>

<script>
function myFunction() {
    var x = document.createElement("DIALOG");
    var t = document.createTextNode("This is an open dialog window");
    x.setAttribute("open", "open");
    x.appendChild(t);
    document.body.appendChild(x);
}
</script>

</body>
</html>