// RequestData(): primary function for performing the AJAX data request
function requestData(subKey, modelNum, returnType, colKey)
{ 
    // alert(subKey + " " + modelNum + " " + returnType + " " + colKey);
    var url;
    xmlHttp = getXmlHttpObject();
    
    if (xmlHttp == null)
    {
      return;
    }
      
    // NOTE: set AJAX request values
    url = "/business/building-products/ventilation-systems/includes/scripts/getXMLData.asp";
    url = url + "?sk=" + subKey;
    url = url + "&mn=" + modelNum;
    url = url + "&type=" + returnType;
    url = url + "&sid=" + Math.random();
    url = url + "&ck=" + colKey;
 
    switch(returnType)
    {
        case "model":
            xmlHttp.onreadystatechange = loadModels;
            break;
        default: 
            xmlHttp.onreadystatechange = loadMedia;
            break;
    }
    // alert(url);
    xmlHttp.open("GET",url,true);
    xmlHttp.send(null); 
}

// LoadModels(): loads all available models into the "ModelSelect" drop down list
function loadModels() 
{ 
   var returnVal;
   var modelNums;
    if (xmlHttp.readyState == 4)
    { 
        returnVal = xmlHttp.responseText;
        //alert(returnVal);
        modelNums = returnVal.split(",");
        
        // NOTE: Remove drop down options, except "Select Model" 
        document.form1.ModelSelect.options.length = 1;
        for(i=0; i < modelNums.length; i++)
        {     
           // NOTE: need to put in a check for dup array values
          document.form1.ModelSelect.options[i+1] = new Option(modelNums[i],modelNums[i])
        
        }
    }
}

// LoadMedia(): loads all of the result values into the "ResultDisplay" <div> area
function loadMedia() 
{ 
    if (xmlHttp.readyState == 4)
    { 
      return document.getElementById('ResultDisplay').innerHTML = xmlHttp.responseText;
    }
}

// GetSelectedValue(name): Helper function returning the selected value of the "CategorySelect" drop down
function getSelectedValue(name)
{
    var sel = document.getElementsByName(name)[0];
    var i = sel.options.selectedIndex;
    return i == -1? "": sel.options[i].value;
}

function getXmlHttpObject()
{
    var xmlHttp= null;
    
    try
      {
        // NOTE: Firefox, Opera 8.0+, Safari
        xmlHttp = new XMLHttpRequest();
      }
    catch (e)
      {
      // NOTE: Internet Explorer
      try
        {
            xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        }
      catch (e)
        {
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
      }
    return xmlHttp;
}