Ajax请求随机失败

Question

whats hapenning is that my ajax request randomly fails, and I don't know why.

I've been testing only in chrome and when the error callback gets called the controller returns successfully so i think that the problem is not in the server side.but i'm not sure. the responseText error in chrome is blank so i have no tip to troubleshoot.

This is My Ajax call m I doing somehting wrong, I'm Clueless?

$.ajax({
    type: "GET",
    url: url,
    data: { postalCode: postalCode },
    dataType: "json",
    success: function (response) {
        if (isPostBack != 'True') {
            switch (response["Code"]) {
                case "-1":
                    alert('msg 1.');
                    break;
                case "0":
                    alert('msg 2.');
                    break;
                case "1":
                    alert('msg 3.');
                    break;
                case "2":
                    alert('msg 4.');
                    break;
                default:
                    alert('unexpected value.');
            }
        }
    }
});

if not what could be the most likely causes? I'm Developing Asp.NET MVC for Sitefinity, and I only detect this issue in this ajax request.

UPDATE:

I've detected in the browser that the request is being cancelled. it arrives successfully to the server and is cancelled during the code execution. it is not cancelled in a specific line because I commented the lines to find which one is causing troubles but it was cancelled regardless of the code line. Then I started thinking about timeout and added a timeout. first 3 seconds than 10 seconds. but the problem was still there. this is the request status:

Answer 1

Suggesting a slight modification:

$.getJSON(url, {"postalCode": postalCode})
 .success(function (response) {
    if (isPostBack != 'True') {
        switch (response.Code) {
        case "-1":
            alert('msg 1.');
            break;
        case "0":
            alert('msg 2.');
            break;
        case "1":
            alert('msg 3.');
            break;
        case "2":
            alert('msg 4.');
            break;
        default:
            alert('unexpected value.');
        }
    }
});