Ajax success event not working

Question

The result is probably not in JSON format, so when jQuery tries to parse it as such, it fails. You can catch the error with error: callback function.

You don't seem to need JSON in that function anyways, so you can also take out the dataType: 'json' row.

Although the problem is already solved i add this in the hope it will help others.

I made the mistake an tried to use a function directly like this (success: OnSuccess(productID)). But you have to pass an anonymous function first:

  function callWebService(cartObject) {

    $.ajax({
      type: "POST",
      url: "http://localhost/AspNetWebService.asmx/YourMethodName",
      data: cartObject,
      contentType: "application/x-www-form-urlencoded",
      dataType: "html",
      success: function () {
        OnSuccess(cartObject.productID)
      },
      error: function () {
        OnError(cartObject.productID)
      },
      complete: function () {
        // Handle the complete event
        alert("ajax completed " + cartObject.productID);
      }
    });  // end Ajax        
    return false;
  }

If you do not use an anonymous function as a wrapper OnSuccess is called even if the webservice returns an exception.

I tried removing the dataType row and it didn't work for me. I got around the issue by using "complete" instead of "success" as the callback. The success callback still fails in IE, but since my script runs and completes anyway that's all I care about.

$.ajax({
    type: 'POST',
    url: 'somescript.php',
    data: someData,
    complete: function(jqXHR) {
       if(jqXHR.readyState === 4) {
          ... run some code ... 
       }   
    }        
 });

in jQuery 1.5 you can also do it like this.

var ajax = $.ajax({
    type: 'POST',
    url: 'somescript.php',
    data: 'someData'
});
ajax.complete(function(jqXHR){
    if(jqXHR.readyState === 4) {
        ... run some code ... 
    }
});

Make sure you're not printing (echo or print) any text/data prior to generate your JSON formated data in your PHP file. That could explain that you get a -sucessfull 200 OK- but your sucess event still fails in your javascript. You can verify what your script is receiving by checking the section "Network - Answer" in firebug for the POST submit1.php.

Put an alert() in your success callback to make sure it's being called at all.

If it's not, that's simply because the request wasn't successful at all, even though you manage to hit the server. Reasonable causes could be that a timeout expires, or something in your php code throws an exception.

Install the firebug addon for firefox, if you haven't already, and inspect the AJAX callback. You'll be able to see the response, and whether or not it receives a successful (200 OK) response. You can also put another alert() in the complete callback, which should definitely be invoked.

I was returning valid JSON, getting a response of 200 in my "complete" callback, and could see it in the chrome network console... BUT I hadn't specified

dataType: "json"

once I did, unlike the "accepted answer", that actually fixed the problem.