Why in the world this ajax call is not working

$(function () {
    $('input#UserName').blur(function () {
        var username = $('input#UserName').val();
        $.ajax(
        {
            type: "POST",
            url: "Profile/CheckAvailability",
            data: "username=" + username,               
            success: function (result) {
                //Some code here
            },
            error: function () {
                alert("Sorry! We could not receive your feedback at this time.");                
            }
        });
    });
});

and the code on Profile controller

    [HttpPost]
    public JsonResult Chec开发者_Python百科kAvailability(string username)
    {
        bool isAvailable = false;
        //Some code here
        return Json(new {success = isAvailable});
    }

Each time alert("Sorry! We could not receive your feedback at this time."); is being triggered.

Thanks.

---

Here are a few tips:

1. Make sure your controller action is not throwing an exception (especially the part where you say //Some code here). This could be verified by stepping through it and debugging.

2. Make sure to always URL encode your request parameters and never use string concatenation:

   data: { username: username },
   

3. Never hardocde urls in your javascript file. Always use Url helpers when dealing with urls (if this is a separate javascript then you could use a global js variable set in your view):

   url: '<%= Url.Action("Profile", "CheckAvailability") %>',
   

4. Use FireBug to see what is being sent to and received from the server.

---

Try setting dataType as "json", because the one you specified isn't valid. Valid dataTypes from jquery documentation: xml, json, jsonp, html, text.

Check out this url about ajax error handling: jQuery Ajax error handling, show custom exception messages