Javascript Section Scrolling with Mousewheel (needs jquery, underscorejs)

scroll.js

var sections = $('[data-tag]:not(.navigation):not(.footer):not(.story-time)'),

    activeSection = null,

    getNextSection = function(){

        var coords = [],
            top = $(window).scrollTop();

        _.each(sections, function(s){

            coords.push({
                top   : $(s).offset().top,
                el    : $(s),
                tag   : $(s).data('tag'),
                height: $(s).outerHeight()
            });

        });

        coords = _.sortBy(coords, 'top');

        possible = _.filter(coords, function(e){
            return e.top > top;
        });

        //possible.length && console.log(possible[0].tag);

        return possible.length ? possible[0] : null;
    },

    nextSection = getNextSection(),

    handleScroll = function(event){

        activeSection = nextSection;
        nextSection = getNextSection();

        if( nextSection ){

            dir = event.originalEvent.wheelDelta || -event.originalEvent.detail;

            if( dir < 0 ){

                if( activeSection && activeSection.height > $(window).innerHeight() ){

                    bottomPos = $(window).scrollTop() + $(window).innerHeight();

                    if( nextSection.top < bottomPos ){

                        $('html, body').stop().animate({
                            scrollTop: nextSection.top + 1,
                        }, 1000, 'easeOutExpo');

                        return false;
                    }
                }
                else {

                    $('html, body').stop().animate({
                        scrollTop: nextSection.top + 1,
                    }, 1000, 'easeOutExpo');

                    return false;

                }
            }
        }
    };

    $(document).on('mousewheel DOMMouseScroll', _.throttle(handleScroll, 500));