Question

I’m trying to access a cross domain .js file using ajax:

$.ajax({
    type:'get',
    crossDomain:true,
    url: "http://localhost/62588/scripts/bootStrapper.js",
    contentType: "application/json",
    dataType: 'jsonp'    
}).done(callback);

I have a callback at the moment:

getBootStrapperScript(function (callback) {         
       //do somethibg
})

I get the following error:

XMLHttpRequest cannot load http://localhost/62588/scripts/bootStrapper.js. Origin http://localhost:62607 is not allowed by Access-Control-Allow-Origin.

I have been reading about JSONP but I’m not sure how to use it to load a .js file from anoather domain.

If I change the above code to use ‘jsonp’ for the datatype but I then get this errer:

GET http://localhost/62588/scripts/bootStrapper.js?callback=jQuery18206067646441515535_1354459693160&_=1354459696966 404 (Not Found) 

How can I load cross domain js files?

Answer 1

Don’t use any AJAX, simply use the $.getScript function:

$.getScript('http://localhost/62588/scripts/bootStrapper.js').done(callback);

As you know, you could be pointing the <script> tag to any domain you wish without violating the same origin policy. That’s the basis of JSONP. But you don’t need any JSONP, because all you need is to reference a script form a remote domain, which is as simple as pointing the <script> tag to this script or if you want to do it dynamically use the $.getScript function that jQuery has to offer you.

---

UPDATE:

The $.getScript function will append a random cache busting parameter to the url. If you want to get a cached version of your script you could define a custom cachedScript function as shown in the documentation:

jQuery.cachedScript = function(url, options) {
    options = $.extend(options || {}, {
        dataType: 'script',
        cache: true,
        url: url
    });
    return jQuery.ajax(options);
};

and then:

$.cachedScript('http://localhost/62588/scripts/bootStrapper.js').done(callback);