how to use status codes 200, 404, 300 ( how jquery done and fail work internally) [closed]

Answer 1

In addition to what @dfsq wrote, you can handle specific status codes:

$.ajax({
  statusCode: {
    404: function() {
      alert( "page not found" );
    }
  }
});

or with deferred:

$.ajax({
    url: "update.php",
    type: "POST",
    data: customObj
})
.fail(function( jqXHR, textStatus, errorThrown) {
    if (jqXHR.status == 403) {
        alert( "forbidden" );
    }
});

or:

$.ajax({
    url: "update.php",
    type: "POST",
})
.statusCode({
    401: function() { alert( 'Unauthorized' ); },
    200: function() { alert( 'OK!'); }
});

Answer 2

If you want to know which status codes there are, check out:

http://de.wikipedia.org/wiki/HTTP-Statuscode

jQuery will work excatly with those.

Answer 3

If you take a look at $.ajax implementation you will find these lines of code:

// Callback for when everything is done
function done(status, nativeStatusText, responses, headers) {

    ...

    // Determine if successful
    isSuccess = status >= 200 && status < 300 || status === 304;

    ...

    // Success/Error
    if (isSuccess) {
        deferred.resolveWith(callbackContext, [success, statusText, jqXHR]);
    } else {
        deferred.rejectWith(callbackContext, [jqXHR, statusText, error]);
    }

    ...
}

So the answer is that codes in range 200-300 and 304 are considered successful, and everything else is a failure. Based on that they resolve (done, success methods will be called) or reject (fail) deferred object.