How to update an array from multiple select

[leetee4000]

Hi,

Im new to javascript / AJAX and would appreciate any help with this.

I have a multiple select box and want to be able to select from this box and transfer the selection accross to a div using an "Add" button. I have this working fine but I want to append to the list, rather than replace the list when further selections are made.

I somehow need the function to remember the original selected array and then merge the new selected array and the old array if another sleection is made. I have no idea how this would be done. Any ideas welcome. This is all I have so far...

function editOptions(action)
{
  var optionsBox = document.getElementById('optionsBox');
  var selectedArray = new Array();
  var selObj = document.getElementById('productOptions');
  var i;
  var count = 0;
  for (i=0; i<selObj.options.length; i++) {
    if (selObj.options[i].selected) {
      selectedArray[count] = selObj.options[i].value;
      count++;
    }
  }


  var strURL="ajax/selected_options.php?options="+newArray;
  
  alert(strURL);
   
   var req = getXMLHTTP();
   if (req)
   {
     req.onreadystatechange = function()
     {
      if (req.readyState == 4)
      {
         // only if "OK"
         if (req.status == 200)
        {
            document.getElementById('optionsBox').innerHTML=req.responseText;
         } else {
           alert("There was a problem while using XMLHTTP:\n" + req.statusText);
         }
       }
      }
   req.open("GET", strURL, true);
   req.send(null);
   }
}