jQuery JSON call to ASP .NET website succeeding in IE but not in Firefox or Chrome

I'm fetching JSON from my ASP .NET website using the following jQuery:

$.ajax({
  type: 'POST',
  url: '/blah/default.aspx/GetTestData',
  contentType: 'application/json; charset=utf-8',
  dataType: 'json',
  success: function(output) {
      var viewModel = $.parseJSON(output.d);
      ko.applyBindings(viewModel);
}

});

And then using the Knockout library to update my UI. The server-side code in default.aspx to get the data is as follows.

[WebMe开发者_运维知识库thod]
public static string GetTestData()
{
    var viewModel = null; // Get viewModel data from elsewhere.
    return new JavaScriptSerializer().Serialize(viewModel);
}

This works fine in IE but when I try in Chrome and Firefox the JSON does not get returned. My breakpoint server-side does get hit so the web method is being called, but something is happening when it comes back to the browser.

I think it might be related to setting content or MIME types at either the browser or webserver end but I've not had any luck yet, does anyone have any suggestions?

---

You can actually avoid the serialization and parsing by having your Page Method just return your object.

So, it would look like:

[WebMethod]
public static ViewModel GetTestData()
{
    var viewModel = createOrGetMyViewModelObjectFromSomewhere();
    return viewModel;
}

On the JavaScript side, it would look like:

$.ajax({
    type: 'POST',
    url: '/blah/default.aspx/GetTestData',
    data: "{}",
    contentType: 'application/json; charset=utf-8',
    dataType: 'json',
    success: function (output) {
        var viewModel = output.d;
        ko.applyBindings(viewModel);
    }
});

So, you don't need to serialize it in .NET and you don't need to parse it on the client-side. It is all handled by the "plumbing" on both sides. Also, passing data: "{}" is important (or if you need parameters, they would go here).

Also, if you were calling a web service instead of Page Method, then you need to decorate the class with a [ScriptService] attribute.

---

What if you remove the contentType param?

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Hey try putting empty data parameter above dataType: 'json', like following

    data: "{}",
dataType: 'json',

that will do a trick!!

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I did not understand clearly. If you can't parse JSON string try this magic code:

var viewModel = eval('(' + data + ')');

where data is your response from server.