Hello @kartik,
You can get the size of the window or document with jQuery:
// Size of browser viewport.
$(window).height();
$(window).width();
// Size of HTML document (same as pageHeight/pageWidth in screenshot).
$(document).height();
$(document).width();
For screen size you can use the screen object:
window.screen.height;
window.screen.width;
Hope it helps!!
Thank you!!