drop down menu - Javascript Get Values from Multiple Select Option Box

Question

This one is driving me nuts. It’s got to be something simple and stupid that I am overlooking. I have a multiple select box in a form. I am just trying to get the values that are selected. In my loop, if I use alert then I have no problem. As soon as try to concatenate the values I get the error ‘SelBranch[...].selected' is null or not an object

      <form name="InventoryList" method="post" action="InventoryList.asp">
          <select name="SelBranch" class="bnotes" size="5" multiple="multiple">
          <option value="All">All</option>
          <option value="001 Renton">001 Renton</option>
          <option value="002 Spokane">002 Spokane</option>
          <option value="003 Missoula">003 Missoula</option>
          <option value="004 Chehalis">004 Chehalis</option>
          <option value="005 Portland">005 Portland</option>
          <option value="006 Anchorage">006 Anchorage</option>
          <option value="018 PDC">018 PDC</option>
          </select>

         <input type="button" name="ViewReport" value="View" class="bnotes" onclick="GetInventory();">

   </form>


   <script language="JavaScript">
       function GetInventory()
       {
         var InvForm = document.forms.InventoryList;
         var SelBranchVal = "";
         var x = 0;

         for (x=0;x<=InvForm.SelBranch.length;x++)
         {
            if (InvForm.SelBranch[x].selected)
            {
             //alert(InvForm.SelBranch[x].value);
             SelBranchVal = SelBranchVal + "," + InvForm.SelBranch[x].value;
            }
         }
         alert(SelBranchVal);
       }


  </script>

Answer 1

The for loop is getting one extra run. Change

for (x=0;x<=InvForm.SelBranch.length;x++)

to

for (x=0; x < InvForm.SelBranch.length; x++)