Tryit Editor v2.9

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

<p>Click the button to open a new window called "MsgWindow" with some text.</p>

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

<script>
function myFunction() {
    var myWindow = window.open("", "MsgWindow", "width=200,height=100");
    myWindow.document.write("<p>This is 'MsgWindow'. I am 200px wide and 100px tall!</p>");
}
</script>

</body>
</html>