cleaning up and upgrading code by using loop for data to be .$post

cleaning up and upgrading code by using loop for data to be .$post

hi all , 
I have a shopping cart with items , quantities and sizes and i am using jquery to post these values to a php page, as i did it i can only handle 4 items in my shopping cart at once, i can add more, by adding to the code the way i am doing it, but i am looking for a better way to do this, that will not have me hard encode it everytime i want to upgrade the number of items allowed (something like a loop with variables ) 
here is what i have :

  1. <script language="javascript">
  2. function add_to_cart() {
  3.       if ($number_of_items == 1){  //$number of items is a global var that 
  4.                                                 //checks how many items in cart 
  5.             post_data2 = {
  6.                   'quanchg1'    : $("#quansel1").val()  ,
  7.                   'itemid1'     : $('input[name=itemid1]').val(), 
  8.                   'sizechg1'    :  $("#size1").val() ,           
  9.             }; // end post_data
  10.       }; // end if 
  11.       if ($number_of_items == 2){
  12.             post_data2 = {
  13.                   'quanchg1'    : $("#quansel1").val()  ,
  14.                   'itemid1'     : $('input[name=itemid1]').val(), 
  15.                   'sizechg1'     :  $("#size1").val() ,    
  16.                   'quanchg2'    : $("#quansel2").val()  ,
  17.                   'itemid2'     : $('input[name=itemid2]').val(),  
  18.                   'sizechg2'     : $("#size2").val() ,          
  19.             }; // end post_data
  20.       }; // end if 
  21.       if ($number_of_items ==3 ){
  22.             post_data2 = {
  23.                   'quanchg1'    : $("#quansel1").val()  ,
  24.                   'itemid1'     : $('input[name=itemid1]').val(), 
  25.                   'sizechg1'     :  $("#size1").val() ,    
  26.                   'quanchg2'    : $("#quansel2").val()  ,
  27.                   'itemid2'     : $('input[name=itemid2]').val(),  
  28.                   'sizechg2'     : $("#size2").val() ,      
  29.                   'quanchg3'    : $("#quansel3").val()  ,
  30.                   'itemid3'    : $('input[name=itemid3]').val(), 
  31.                   'sizechg3'     :  $("#size3").val() ,                      
  32.             }; // end post_data
  33.       }; // end if 
  34.       if ($number_of_items ==4){
  35.             post_data2 = {
  36.                   'quanchg1'    : $("#quansel1").val()  ,
  37.                   'itemid1'     : $('input[name=itemid1]').val(), 
  38.                   'sizechg1'     :  $("#size1").val() ,    
  39.                   'quanchg2'    : $("#quansel2").val()  ,
  40.                   'itemid2'     : $('input[name=itemid2]').val(),  
  41.                   'sizechg2'     : $("#size2").val() ,      
  42.                   'quanchg3'    : $("#quansel3").val()  ,
  43.                   'itemid3'    : $('input[name=itemid3]').val(), 
  44.                   'sizechg3'     :  $("#size3").val() ,     
  45.                   'quanchg4'    : $("#quansel4").val()  ,
  46.                   'itemid4'     : $('input[name=itemid4]').val(), 
  47.                   'sizechg4'     :  $("#size4").val() ,                
  48.             }; // end post_data
  49.       }; // end if 
  50.       $.post('update_cart.php', post_data2, function(data){  
  51. $("#lcart<?php echo $divid ?>").html(data);
  52.       });
  53.  }

i was thinking of something like this (i know it doesnt work this way)

  1. var $x ,
  2. $x = 0,
  3. while ($x < $number_of_items)
  4.       $x = $x+1;
  5.             post_data2 = {  
  6.                   'quanchg'+$x    : $("#quansel"+$x).val()  ,
  7.                   'itemid'+$x     : $('input[name=itemid'+$x+']').val(), 
  8.                   'sizechg'+$x     :  $("#size"+$x).val() ,        
  9.             }; // end post_data
  10. } //end while