Question

How can I get the previous selected index on change event of dropdown list using Javascript.

Answer 1

No, it is not possible, but you can use a variable inside onchange event that tracks the previous selection

Example:

var previousSelected;
function track(d){
  if(typeof previousSelected != 'undefined'){
    alert("Previous selected value " + previousSelected );
  }
  previousSelected = d.selectedIndex;
  alert("selected value " + d.selectedIndex); 
}