Detecting if an element is in the Viewport : jQuery

isInViewport.js

    $.fn.isInViewport = function() {
        var elementTop = $(this).offset().top;
        var elementBottom = elementTop + $(this).outerHeight();

        var viewportTop = $(window).scrollTop();
        var viewportBottom = viewportTop + $(window).height();

        return elementBottom > viewportTop && elementTop < viewportBottom;
    };