Question

In my sample code, I have 2 dropdownlists (but in the real code the number varies because the dropdownlists are created dynamically) and what I wanted to do is to count how many dropdownlists are selected with a non-zero value. I used closure to keep track of the total number of dropdownlists with non-zero selected value. I was successful in doing that (refer to http://jsfiddle.net/annelagang/scxNp/9/).

Old/Working Code

$("select[id*='ComboBox']").each(          
          function() {              
              $(this).change(
                  function() {
                      compute(this);
              });         
      });

    var compute = (function () {
    var total = 11; 
    var selectedDdl = [];

    $("#total").text(total);     
    return function (ctrl) {
         var id = $(ctrl).attr("id");
         var ddlMeal = document.getElementById(id);
         var found = jQuery.inArray(id, selectedDdl);

        if (ddlMeal.options[ddlMeal.selectedIndex].value != 0){
             if(found == -1){
                 total += 1; 
                 selectedDdl.push(id);        
             } 
             else{
                 total = total;
             }
         }
         else {
             total -= 1;
             var valueToRemove = id;
             selectedDdl = $.grep(selectedDdl, function(val) 
                                      { return val != valueToRemove; });
         }        

         $("#total").text(total); 
    };     
}());

Note: I initialized the total variable with 11 because as I mentioned in the real code I can have more than 2 dropdownlists and I just wanted to test if my code will work on values more than 2.

When I tried transferring the closure inside the .change() event, it no longer works (see http://jsfiddle.net/annelagang/scxNp/12/) Could somebody please help me figure this one out? I’ve been doing this code for a few days now and it’s getting quite frustrating.

New/Non-working code:

$("select[id*='ComboBox']").each(          
          function() {              
              $(this).change(
                  function() {
                     (function () {
                var total = 11; 
                var selectedDdl = [];

                $("#total").text(total);     
                return function (ctrl) {
                     var id = $(ctrl).attr("id");
                     var ddlMeal = document.getElementById(id);
                     var found = jQuery.inArray(id, selectedDdl);

                     if (ddlMeal.options[ddlMeal.selectedIndex].value != 0){
                         if(found == -1){
                             total += 1; 
                             selectedDdl.push(id);        
                         } 
                         else{
                             total = total;
                         }
                     }
                     else {
                         total -= 1;
                         var valueToRemove = id;
                         selectedDdl = $.grep(selectedDdl, function(val) 
                                           { return val != valueToRemove; });
                         }        
                    $("#total").text(total); 
                };     
        }());
          });         
      });

Thanks in advance.

P.S. I’m also open to less messier solutions.

Answer 1

I believe this should work:

$("select[id*='ComboBox']").change(function() {
    $("#total").text($("select[id*='ComboBox'][value!=0]").length);
});

http://jsfiddle.net/scxNp/15/