[jQuery] What does this do?

[Danjojo]

Sorry not a quiz... I just am having trouble remembering how I built
this.

What does this do?

firstInt = Number($("div#upsell .upsell_feature_module:visible").attr
("id"));

Is it counting where in the chain of Div's the current position is?

My code is:

function scrollCartUpsells(num){
        if (Number(num) == 1){
            firstInt = Number($
("div#upsell .upsell_feature_module:visible").attr("id"));
            alert(firstInt);
            nextInt = Number(firstInt) + 1;
            prevInt = Number(firstInt) - 1;
            lastInt = Number(firstInt) + Number(spanInt); // lastInt
gets display: none;
        }
        if (Number(num) == -1){
            firstInt = Number($
("div#upsell .upsell_feature_module:visible").attr("id")) -1;
            nextInt = Number(firstInt) + 1;
            prevInt = Number(firstInt) - 1;
            lastInt = Number(firstInt) + Number(spanInt); // lastInt
gets display: none;
        }

            // ******** ******** BUTTON VISIBILITY CONTROLS ********
********
            if(Number(firstInt) > 0) {
                $("#scrollLeft").removeClass("none");
            }
            if(Number(firstInt) <= 1) {
                $("#scrollLeft").addClass("none");
                if(Number($("div#upsell .upsell_feature_module:visible").attr
("id")) == 1){
                $("#scrollLeft").removeClass("none");
                }
            }
        if(Number(lastInt) >= Number(endInt)) {
            $("#scrollRight").addClass("none");
        }
                if(Number(lastInt) < Number(endInt)) {
            $("#scrollRight").removeClass("none");
        }
        // ******** ******** BUTTON VISIBILITY CONTROLS ********
********


            if (Number(num) == 1){
                $("#"+firstInt).addClass("none");
                $("#"+firstInt).css('margin-left', '5px');
                $("#"+nextInt).css('margin-left', '40px');
                    $("#"+lastInt).removeClass("none");
                }
            if (Number(num) == -1){
            lastInt = Number(firstInt) + Number(spanInt);
                $("#"+firstInt).removeClass("none");
                $("#"+firstInt).css('margin-left', '40px');
                $("#"+nextInt).css('margin-left', '5px');
                    $("#"+lastInt).addClass("none");
                    $("#scrollRight").removeClass("none");
        }
}