ajax Callbacks Interpreting errors with "error" callback

Example

Errors, when managed properly by the server, will be returned to your client with a specific HTTP status code different from 2xx (see RFC 2616 section 10).

It's advised to catch globally your errors from your $.ajaxSetup() as demonstrated in the example below. Therefore all errors coming from your ajax calls will be automatically interpreted from the ajax setup.

$.ajaxSetup({
    error: function (jqXHR, exception, errorThrown) {
        var message;
        var statusErrorMap = {
            '400': "Server understood the request, but request content was invalid.",
            '401': "Unauthorized access.",
            '403': "Forbidden resource can't be accessed.",
            '500': "Internal server error.",
            '503': "Service unavailable."
        };
        if (jqXHR.status) {
            message = statusErrorMap[jqXHR.status];
            if (!message) {
                message = "Unknown Error.";
            }
        } else if (exception == 'parsererror') {
            message = "Error.\nParsing JSON Request failed.";
        } else if (exception == 'timeout') {
            message = "Request Time out.";
        } else if (exception == 'abort') {
            message = "Request was aborted by the server";
        } else {
            message = "Unknown Error.";
        }

        // How you will display your error message...
        console.log(message);
        console.log(errorThrown);
    }
});

You may also want to "overload" the error callback in a specific $.ajax() when you are waiting for a specific error message.

$.ajax({
    url: './api',
    data: { parametersObject },
    type:'post',
    dataType: 'json',
    success:function(output){
        // Interpret success
    },
    error: function(xhr,textStatus,ErrorThrown){
        // Specific error will not be interpreted by $.ajaxSetup
    }
});