跟踪jQuery可排序中所有元素的位置

I'm trying to figure out how I can track how the elements in a jQuery sortable. Let's say that I have four elements (divs) in my sortable, each have an unique id. Let's call them #100, #200, #300 and #400 and they're presented in that order to start with. But when I move #100 to let's say spot number 3, I need to be able to save the new position for this id, but also make sure that the other ones get updated position values aswell.I'm trying to figure out how I can track how th