how to click to know the position in sortable list

how to click to know the position in sortable list

    i have the following code to get the change of position, I dont know how to make the list tell me the position of a specific element when i click it. 

    please give some idea.

    3. $( "#sortable" ).sortable(
    4. {
    5.                start:function(event, ui) {
    6.  startpos=( $(ui.item).prevAll().length );
    7.                },

    9.                stop:function(event, ui) {
    10.                        stoppos=($(ui.item).prevAll().length );
    11.                }
    12. });