Get viewport size (Nice)

var w = window,
d = document,
e = d.documentElement,
g = d.getElementsByTagName('body')[0],
x = w.innerWidth || e.clientWidth || g.clientWidth,
y = w.innerHeight|| e.clientHeight|| g.clientHeight;
alert(x);
alert(y);

Reference url: http://stackoverflow.com/questions/3437786/how-to-get-web-page-size-browser-window-size-screen-size-in-a-cross-browser-wa