How many px width and heigh is the output in codeplayground?

Answer 1

The output in codeplayground isn't fixed: it depend of the device and the interface used: the viewport will have different sizes for each device, and using web site or app' interface will not provide same layouts (as well as depending of orientation and mobile type -- on phones landscape orientation is disabled, but on tablet it will change a few the layout, but almost change the viewport size when device is rotated)...

Answer 2

Use this Jacascript:
alert(window.innerWidth+"x"+window.innerHeight)

Answer 3

It might be best to use this instead @Frans:
window.onload = function (){ alert(window.innerWidth+"x"+window.innerHeight)
}