[jQuery] What does this do?

[jQuery] What does this do?


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");
    }
}