javascript - give a value to input when move then save it by ajax - php / jquery -php -

i want create shopping cart , i'm finish. use ajax dynamic search , ajax add cart , use jquery refresh specific div when click face problem.my problem quantity problem. use session store value //this session update code

$con = mysqli_connect("localhost", "root" , "","atest"); session_start();     require("functions.php");     cart_session(); $id=$_post['id'];         //echo $arr['cart'];          if(isset($_session[$arr["cart"]][$id])){              $_session[$arr["cart"]][$id][$arr["quantity"]]++;             //redirect("http://localhost/my/work/sellingcart/index.php",true);          }else{              $sql_s="select * product_1                 p_id={$id}";             //echo $sql_s;             $query_s=mysqli_query($con,$sql_s);             if(mysqli_num_rows($query_s)!=0){                 $row_s=mysqli_fetch_array($query_s);                  $_session[$arr['cart']][$row_s["p_id"]]=array(             "{$arr["quantity"]}" => 1                     );                  //redirect("http://localhost/my/work/sellingcart/index.php",true);             }else{                  $message="this product id it's invalid!";              }          } 

//use ajax update cart

 <script>            $("#link").click(function(e) {   e.preventdefault();   var id = $("#id").val();     var datastring = 'id='+id;     $('#loading-image').show(); $(".form :input").attr("disabled", true); $('#remove_cart').hide(); $('#link').hide();  $(".container").css({"opacity":".3"});    $(".form :input").attr("disabled", true); $('#remove_cart').hide(); $('#link').hide();   $.ajax({     type:'post',     data:datastring,     url:'add_cart.php',     success:function(data) {       $('#availability').html(data);       },     complete: function(){         $('#loading-image').hide();         $(".form :input").attr("disabled", false);         $('#remove_cart').show();         $('#link').show();         $(".container").css({"opacity":"1"});        }   }); //$("#chat").load(location.href + " #chat"); //$("#chat").load(location.href+" #chat>*",""); });    </script> 

here image , red mark problem.

i want update cart when give value , move update session ajax , php.

is there help? don't want user can update there quantity every cart item singly. want dynamic give quantity number , move save ajax.

assign onchange event quantity input boxes:

$('input[name=quantitybox]').change(function() { ... }); 

in function() above, add ajax post request containing like

var quantity = $('input[name=quantitybox]').val(); // var id = something; $.ajax({     type:'post',     data:"productid=" + id + "&updatequantity=" + quantity,     url:'add_cart.php',     success:function(data) {         $('#availability').html(data);       },     complete: function(){         // want on successful update of request     } }); 

in php function above, check whether product exists in user's cart. @ point, change quantity.

 if(isset($_session[$arr["cart"]][$id])){          $quantity = $_post['updatequantity'];         $id = $_post['productid'];         $_session[$arr["cart"]][$id][$arr["quantity"]] = $quantity;   }