SyntaxError: JSON.parse: unexpected non-whitespace character

Question

Hello Everyone,

Below is my Webmethod
[WebMethod]
public void GetAllEmployee(string month, string year)
{
try
{
DBHelper oDBhelper = new DBHelper();
DataTable dt = new DataTable();
List employeelist = new List();
Hashtable param = new Hashtable();
param.Add("@Case ", 3);
param.Add("@bmonth", month);
param.Add("@byear", year);
dt = oDBhelper.GetDatatabel("usp_OC_balance_details", param);

            for (int i = 0; i < dt.Rows.Count; i++)  
            {  
                EmployeeWithOCBalance employee = new EmployeeWithOCBalance();  
                employee.emp_id = dt.Rows[i]["emp_id"].ToString();  
                employee.name = dt.Rows[i]["name"].ToString();  
                employee.opening_balance = dt.Rows[i]["opening_balance"].ToString();  
                employee.closing_balance = dt.Rows[i]["closing_balance"].ToString();  
                employeelist.Add(employee);  
            }  
            JavaScriptSerializer js = new JavaScriptSerializer();  
            Context.Response.Write(js.Serialize(employeelist));  
        }  
        catch (Exception ex)  
        {  
  
  
        }  
    }

And this is my Ajax method

function BindEmployees(month,year) {  
            $.ajax({  
                url: 'Assets.asmx/GetAllEmployee',  
                data: '{ "month": "'+month+'", "year": "'+year+'" }',  
                dataType: "json",  
                method: 'POST',  
                contentType: 'application/json',  
                success: function (data) {  
.......................... so on

I am getting method repose code as 200.
When I get the json response, it adds {"d":null} at the very last.
I don't know from where it is coming.
The result is I am not able to bind the data in a table.

Kindly suggest.
Thanks

Answer

When I get the json response, it adds {"d":null} at the very last. I don't know from where it is coming.

I guess it is "d" property added by ASP.NET Web Servce after and including ASP.NET 3.5 for security reason and content (null because nothing returned). For details please refer to the following article:

Handling JSON Arrays returned from ASP.NET Web Services with jQuery
https://www.mikesdotnetting.com/Article/96/Handling-JSON-Arrays-returned-from-ASP.NET-Web-Services-with-jQuery

Answer

Answer

Answer

webmethods were designed to return data objects to javascript. for security the object is returned as

{"d": object}

so in jQuery you always needed to use result.d to get the data.

your method is writing out json, unknown to the web method render code, and does not return an object, so it appends its response.

follow the docs

https://learn.microsoft.com/en-us/aspnet/web-forms/overview/older-versions-getting-started/aspnet-ajax/understanding-asp-net-ajax-web-services

SyntaxError: JSON.parse: unexpected non-whitespace character

4 answers