This is super old, but hopefully this helps somebody. I'm sending responses with different error codes back and this is the only solution I've found that works in
$.ajax({
data: {
"data": "mydata"
},
type: "POST",
url: "myurl"
}).done(function(data){
alert(data);
}).fail(function(data){
alert(data.responseText)
});
Since JQuery deprecated the success and error functions, it's you need to use done and fail, and access the data with data.responseText when in fail, and just with data when in done. This is similar to @Marco Pavan 's answer, but you don't need any JQuery plugins or anything to use it.