Sort select:option list with a callback function

gistfile1.js

/** 
credits to: http://stackoverflow.com/questions/1134976/how-may-i-sort-a-list-alphabetically-using-jquery
          : http://stackoverflow.com/questions/278089/javascript-to-sort-contents-of-select-element
and a little hacks there by 3emad
**/

function sortUnorderedOption(select,callback_fun) {
    selElem = document.getElementById(select);
    var tmpAry = new Array();
            for (var i=0;i<selElem.options.length;i++) {
                    tmpAry[i] = new Array();
                    tmpAry[i][0] = selElem.options[i].text;
                    tmpAry[i][1] = selElem.options[i].value;
            }

            tmpAry.sort(function(x,y){ 
                var a = String(x).toUpperCase(); 
                var b = String(y).toUpperCase(); 
                if (a > b) 
                    return 1 
                if (a < b) 
                    return -1 
                return 0; 
                }); 
            while (selElem.options.length > 0) {
                selElem.options[0] = null;
            }
            for (var i=0;i<tmpAry.length;i++) {
                    var op = new Option(tmpAry[i][0], tmpAry[i][1]);
                    selElem.options[i] = op;
            }

            if(typeof callback_fun != 'undefined'){
                selElem = callback_fun(selElem);
            }
            return;
}
/** end function **/


/*
 * EXAMPLE of a callback
 * // the following example failed to keep the last index.
 * i.e
 * temp = selElem.options[0];
 * selElem.options[0] = selElem.options[1];
 * selElem.options[1] = temp
 * return;
 */
var replace_index = function(selElem){ // callback used to change places of elements
  var dash = selElem.options[0];
  var all  = selElem.options[1];
  selElem.options[0] = new Option(all.innerHTML, all.value);
  selElem.options[1] = new Option(dash.innerHTML, dash.value);
  return selElem;
}

/** Usage **/
sortUnorderedOption('select_category',replace_index); // select_category is an ID of a select