It isn't obvious how to get the error text returned (either in the status or the response) in $.ajax's error handler if you're not already all over XmlHttpRequest. Something like this maybe:

$.ajax({

type: "POST",

url: "delete.php",

data: "id=INVALID",

success: function(data){

alert("Success: " + data);

},

error: function(req, status, error) {

alert("Error (status): " + req.statusText);

alert("Error (response): " + req.responseText);

}

});