Ajax和Node.js出现问题

Question

I am having a problem that has me perplexed.

I have a simple webpage that works using php and mysql. I am trying to conver this to node.js and mysql.

There are 2 dropdown select boxes the first contains a list of customers that is taken from the database. (This works well)

when a customer is selected I need the second box to contain a list of instruments that belong to the customer.

I have this working great in the php version but in the node.js version the second dropdown does not get up[dated and the console has and error that states Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience.

Does this mean I can not use this code or better yet how do I change this script to make it work properly??

$(document).ready(function(){ 

$("select#cust").change(function(){
var cust_id =  $("select#cust option:selected").attr('value'); 
var test =  $("#test").val();
var din = $("#idate").val(); 
$("#inst").html( "" );

if (cust_id.length > 0 ) { 
$.ajax({
        async: true,
        type: "GET",
        async: true,
        url: "fetch_inst",
        data: "cust_id="+cust_id,
        cache: false,
        beforeSend: function () { 
            $('#inst').html('<img src="loader.gif" alt="" width="24" height="24">');
        },
        success: function(data) {    
            $("#inst").html( data );

        }
    });

     }
});