how to know the screen size in js code example

Example 1: java script find screen size of device

// Size of browser viewport.
$(window).height();
$(window).width();

// Size of HTML document (same as pageHeight/pageWidth in screenshot).
$(document).height();
$(document).width();

Example 2: js know size of screen

alert("Your screen resolution is: " + screen.width + "x" + screen.height)