javascript - jQuery .post is working but triggering .fail without any information -

i've got data posting i'm not having luck getting .post response handler code work. inconsistent results in different browsers/tools i've tried. here's post code:

$.post(form.attr("action"), form.serialize(), "json")    .done(function (response, textstatus, jqxhr) {       alert('done');    })    .fail(function (jqxhr, textstatus, errorthrown) {       // log error console       alert('responsetext:' + jqxhr.responsetext + ', status:' + textstatus + ', error:' + errorthrown);    }) 

in firefox , chrome goes .fail (even though data posting) item set textstatus "error". in firefox when try view response shows error, "syntaxerror: json.parse: unexpected end of data @ line 1 column 1". in chrome, in console i'm seeing this: "xmlhttprequest cannot load http://example.net/applicationsvc/formprocessor/index.php. no 'access-control-allow-origin' header present on requested resource. origin 'http://example.net' therefore not allowed access." seems relevant attempts solve haven't worked.

how can resolve access-control-allow-origin issue in .post? why aren't getting error data , why firefox unable parse response.

using postman, , using same headers , body, see i'm getting response of:

{"successful":true,"thankyou_message":"<h2>thank you!<\/h2><p>thank signing up!<\/p>"} 

but code doesn't seem getting or handling that.

here request headers going out:

host: example.net user-agent: mozilla/5.0 (windows nt 6.3; wow64; rv:38.0) gecko/20100101 firefox/38.0 accept: */* accept-language: en-us,en;q=0.5 accept-encoding: gzip, deflate content-type: application/x-www-form-urlencoded; charset=utf-8 referer: http://example.net/mypage.htm content-length: 655 origin: http://example.net connection: keep-alive pragma: no-cache cache-control: no-cache 

update: i've switched .post .ajax

$.ajax({     url: form.attr("action"),     type: "post",     data: form.serialize(),     datatype: "json",     contenttype: "application/json; charset=utf-8",     success: function () {         alert('done');     } }); 

with consistent http 501 response.

try enable cross-origin on server, example in php

header("access-control-allow-origin: *"); 

the server must send in response header, change star accordingly domain security reasons.