getViewport

viewport

function getViewport() {

    var viewPortWidth;
    var viewPortHeight;

    // the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight
    if (typeof window.innerWidth != 'undefined') {
        viewPortWidth = window.innerWidth,
        viewPortHeight = window.innerHeight
    }

    // IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
    else if (typeof document.documentElement != 'undefined' && typeof document.documentElement.clientWidth !=
        'undefined' && document.documentElement.clientWidth != 0) {
        viewPortWidth = document.documentElement.clientWidth,
        viewPortHeight = document.documentElement.clientHeight
    }

    // older versions of IE
    else {
        viewPortWidth = document.getElementsByTagName('body')[0].clientWidth,
        viewPortHeight = document.getElementsByTagName('body')[0].clientHeight
    }
    return [viewPortWidth, viewPortHeight];
}