Question

I’m having some troubleS with the iTunes Search API. I can see the data when I access it directly via URL (i.e. http://itunes.apple.com/search?term=Reeder&country=fr&entity=software), but when I try it via a simple script, the data won’t load.

var xhr = new XMLHttpRequest();

xhr.open('GET', 'http://itunes.apple.com/search?term=Reeder&country=fr&entity=software');
xhr.send();

xhr.addEventListener('readystatechange', function () {
    if (xhr.readyState === xhr.DONE && xhr.status === 200) {
        alert(xhr.responseText);
    }
}, false);

Does anybody know what’s going on?

Answer 1

As others said, your request violates same origin policies.

I had this problem a while ago and used YQL to create a JSONP callback (wraps the data in a javascript function). In other words, the script tag is not subject to same-origin policies

YQL: http://developer.yahoo.com/yql/
JSONP: http://en.wikipedia.org/wiki/JSONP (I’m assuming you know JSON)

You can learn the details yourself (how to use JSONP), so I’ll just give you the example.

Your YQL query would be select * from json where url='http://itunes.apple.com/search?term=Reeder&country=fr&entity=software'. If you change the type to JSON (in the console) you can specify a callback for JSONP. Console: http://developer.yahoo.com/yql/console
Link

You create a script tag and set the link/url above as the source. As you can see, the JSON data is wrapped with a function name. You should have defined the callback function, which will be called when the YQL/JSON source is loaded. That callback function then deals with the JSON data.