Test if dropdown menu is off the screen

gistfile1.txt

$(".dropdown li").on('mouseenter mouseleave', function (e) {
    var elm = $('ul:first', this);
    var off = elm .offset();
    var l = off.left;
    var w = elm.width();
    var docW = $(".container").width();

    var isEntirelyVisible = (l+ w <= docW);

    if ( ! isEntirelyVisible ) {
        $(this).addClass('edge');
    } else {
        $(this).removeClass('edge');
    }
});