$.ajax().success not working only in firefox - ajax

Question

I have an ajax function like so:
function RunSubmit() {
$.ajax({
url: '#Url.Action("Contact", "Public")',
type: "POST",
data: $('#contactForm').serialize(),
dataType: 'jsonp',
crossDomain: true,
success: function (result) {
alert("hit success function");
if (result.validForm) {
alert("At redirect. Url is: " + result.url);
window.location.assign(result.url);
//console.log("valid form");
} else {
$('#registerForForm').html(result);
//console.log("BAD FORM");
alert("ELSE CALLED");
}
},
error : function(ob1, ob2, ob3)
{
},
complete: function(val)
{
//This is being hit but it appears no value is being returned from the controller (FireFox)
}
});
Strange thing is it works in IE and Chrome but not FF. I have tried running the post with dataType: 'json' without the dataType and without the crossDomain property. Looking at the console on FF I can see that we are having numerous cross domain request errors mainly coming from google fonts. (This does not happen on chrome or ie). In our controller we are making a hardcoded http request to another server on a different host so I can see where the issue might be arising. The way we have dealt with this issue before is by adding a crossdomain.xml file to the root of our project. Something like this
<?xml version="1.0" encoding="utf-8" ?>
<cross-domain-policy>
<allow-access-from domain="*.xyz.com"/>
<allow-access-from domain="*.abc.com"/>
<allow-access-from domain="*.123.net"/>
<allow-access-from domain="http://university.abc.com"/> //this is the site we are sending a request to in our controller
</cross-domain-policy>
So I have searched and come across multiple posts on SO where the success function was not being called on an ajax post. Check my error objects the only information I am getting back is "error". This javascript should be receiving a url back and redirecting; however, what it is doing is rendering the JSON return value to the screen.
This is the line of code that returns our Json from our controller.
return Json(new { validForm = true, url = "/Public/ContactComplete" }, JsonRequestBehavior.AllowGet);
The line looks fine to me and the Json being returned is perfect json so it should not be a parsing error on the jquery side.

Answer 1

This was an interesting situation. I'm adding this to my list of reasons as to why a form may not post back in MVC. The outside firm we hired to develop our product created a 'hack' to get around an issue where Chrome would not post back if you wished to disable the submit button (to prevent double post) on the click of the button itself. To get around this the developer wrote an ajax script submitting the form manually on click. This in turn blew up functionality in firefox. There was some weird double posting going on and for whatever reason FF would render JSON to the screen instead of catching the Json back and running the success function.
Long story short:
If you are disabling a submit button to prevent double post then disable it on the form submit event.
pseudo code
$('#submit-button').on('click', function() { this.attr('disabled', true);}
Is not the way to go. The below is what fixed it for me
$('form').on('submit', function() { $('#submit-button').attr('disabled', true);}