Passing Local Storage Variable to AJAX URL?

How can I pass a local storage variable into the AJAX url: My problem is the variable "url" won't pass into the url section where I put + url +

Any help would be greatly appreciated. Thanks John

<script id="source" language="javascript" type="text/javascript">

  $(function () 
  {
   $.ajax({

      var url = localStorage.getItem('iphoneusername');
      url: 'http://' + url + '.com/iphone/adddisplayapi.php',                            
      data: "",                                                        
      dataType: 'json',                      
      success: function(data)          
      {
    var id = data[0];             
        var name = data[1];          
    var pic1 = data[2];           


    document.write(name); 
    document.write("<br/>");    
    document.write(id);
    document.write("<br/>");    

    } 
    });
  }); 

  </script>

Try:

$(function () {
 var urlParam = localStorage.getItem('iphoneusername');
   $.ajax({     
      url: 'http://' + urlParam + '.com/iphone/adddisplayapi.php',                            
      data: "",                                                        
      dataType: 'json',                      
      success: function(data) {
       ....rest of your code