<!DOCTYPE html>
<html>
<body>
<p>Open a new window, and resize the width and height to 250px:</p>
<p><b>Tip:</b> Press the "Resize window" multiple times (the window will increase 250px for each press).</p>
<button onclick="openWin()">Create window</button>
<button onclick="resizeWin()">Resize window</button>
<script>
var myWindow;
function openWin() {
myWindow = window.open("", "", "width=100, height=100");
}
function resizeWin() {
myWindow.resizeBy(250, 250);
myWindow.focus();
}
</script>
</body>
</html>