Question

I am just trying to figure out the deferred api and have this nice sample code going with the twitter search api:

var getTweets = function(q) {
    return $.ajax({
        url: 'http://search.twitter.com/search.json?q=' + encodeURIComponent(q),
        dataType: 'jsonp'
    })
};

var getTheDay = function(date){
    var date = new Date(date);
    return date.getDay();
}

var parseTweetData = function(data){
    $.each(data.results, function(index, tweet){
        console.log(tweet.text 
        + ' from ' + tweet.from_user_name 
        + ' at ' + getTheDay(Date.parse(tweet.created_at) * 1000));
    });
}

var parseError = function(error, xhr) {
    alert('failed')
};

$.when(getTweets(' martin')).then(parseTweetData, parseError);

Getting results back is just fine. The problem comes with the situation where twitter returns a 403 error.

I want to handle that error with my custom error handler but that doesn’t seem to be triggered at all. What am I doing wrong? Have I misunderstood the api? How do I write a proper ajax error handler request?

Answer 1

According to the $.ajax docs the error handler isn’t called for jsonp requests, so it probably wont call in a deferred either.

error
Type: Function( jqXHR jqXHR, String textStatus, String errorThrown )
A function to be called if the request fails. The function receives three arguments: The jqXHR (in jQuery 1.4.x, XMLHttpRequest) object, a string describing the type of error that occurred and an optional exception object, if one occurred. Possible values for the second argument (besides null) are “timeout”, “error”, “abort”, and “parsererror”. When an HTTP error occurs, errorThrown receives the textual portion of the HTTP status, such as “Not Found” or “Internal Server Error.” As of jQuery 1.5, the error setting can accept an array of functions. Each function will be called in turn. Note: This handler is not called for cross-domain script and JSONP requests. This is an Ajax Event.

you can try using a timeout to trigger an error callback, so basically we are giving the request some amount of time to be made and when the time expires we assume the request failed.

$.ajax({
    url: 'http://search.twitter.com/search.json?q=' + encodeURIComponent(q),
    dataType: 'jsonp',
    timeout: 5000 /* 5 seconds timeout, plenty of time for the request to complete */
})