screen
The screen object represents screen information. Commonly used attributes are:
screen.width: screen width, in pixels;
screen.height: Screen height, in pixels;
screen.colorDepth: Returns the number of color digits, such as 8, 16, 24.
<html> <head> <script> 'use strict'; alert('Screen size = ' + screen.width + ' x ' + screen.height); </script> </head> <body> </body> </html>rrree