Question

This is the first time i am playing with Ajax. I am trying to just create a basic login at the moment. Anyways i have the following script..

     <script language = "javascript">
            function Login() {  

                       $.ajax({
                        type: "POST",
                        url: "ajax.aspx/Login",
                        data: '{' +
                                'username:"' + $('#username').val() + '",' +
                                'password:"' + $('#password').val() + '"' +
                               '}',
                        contentType: "application/json; charset=utf-8",
                        dataType: "json",
                        success: function(msg) {
                            alert("alert1");
                            var data = json_parse(msg.d);
                            alert("alert2");
                            if (!data.error) {
                                alert("No Error);
                            }
                            else {
                                alert(data.error);
                            }
                        },
                        error: function(msg) {
                            alert('Failure: ' + msg);
                        }
                    });         

            }
    </script>

For some reason it does not run anything after var data = json_parse(msg.d);

It shows the first two alerts but noting after.

the ajax page has the following `

[WebMethod]
public static string Login(string username, string password)
{
    return "{\"error\": \"No IDs\"}";
}

Answer 1

Whats inside the function json_parse? That function could be the source of your error.
A better method to parse JSON is like this.

1. Go to Douglas Crockford’s Github JSON-js/json2.js and copy it
2. Minify it at jscompress.com and copy the compressed code ( can skip this step )
3. Paste it somewhere in your Application folder as json2.js

4. Now reference the script at the page you are pulling data from
   <script src="path/to/script/json2.js" type="text/javascript"></script>

5. Now inside the function, parse your JSON like this.
   var data = JSON.parse(msg.d);

On an un-related side note, its better if you change your error like this to catch errors effectively.

error: function (xhr, status, error) {
    alert(xhr.statusText);
}

Also, call WebMethod like this.

[WebMethod]
public static string Login(string username, string password)
{
    JavaScriptSerializer js = new JavaScriptSerializer();
    dynamic obj = new ExpandoObject();
    obj.error = "No IDs";
    string str = js.Serialize(obj);
    return str;
}