var JSS = {

    counter: -1,
    getFeed: function(url, callback) {
    
        this.counter ++;
        JSS[this.counter] = callback;
        var body = document.getElementsByTagName('body')[0];
        var script = document.createElement('script');
        script.type = 'text/javascript';
        script.src = url + '?callback=JSS[' + this.counter + ']';
        body.appendChild(script);
    }
};