How to get Cost center in the catalog form

Hi,

I have a requirement to show the cost center in the catalog form from the custom table.

In the custom table we have only user id.

On change of user id in the form cost center should populate.

Script include:

var requestor_details = Class.create();
requestor_details.prototype = Object.extendsObject(AbstractAjaxProcessor, {
    getUserDetailsInternal: function() {
        var userName = this.getParameter('sysparm_user');
        var result = "";
        var costing = new GlideRecord("u_custom_user");
        costing.addEncodedQuery('u_useridISNOTEMPTY');
        costing.query();
        if (costing.next()) {
            var cost = costing.u_userid;
            var user = new GlideRecord('sys_user');
            user.addQuery('user_name', cost);
            user.query();
            while (user.next()) {
                result = user.cost_center.getDisplayValue();
            }
        }
        return JSON.stringify(result);
    },
    type: 'requestor_details'
});

Client script:

 var user_id = g_form.getValue('requested');
    var ga = new GlideAjax('requestor_details'); 
    ga.addParam('sysparm_name', 'getUserDetailsInternal'); 
    ga.addParam('sysparm_user', user_id); 
    ga.getXML(EmployeeDetailsLookup); 
}
function EmployeeDetailsLookup(response) {
    var answer = response.responseXML.documentElement.getAttribute("answer");
    var result = JSON.parse(answer);
	alert(result);
    g_form.setValue('cost', result);
}

Please help in this.

Thank you!

Samiksha