function callApi(params, callback){
                var xhr = new XMLHttpRequest();

                xhr.onreadystatechange = function(){
                        if(this.readyState == 4){
                                callback(this.responseText);
                        }
                }

                var post = "";
                if(params.post != null){
                for(var key in params.post){
                        var val = params.post[key];

                        post += "&" + key + "=" + val;

                }

                post = post.substr(1, post.length);
                }
                xhr.open(params.type, '/index.php?option=com_apicart&task=' + params.method);
                xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
                xhr.setRequestHeader("Content-length", post.length);
                xhr.setRequestHeader("Connection", "close");

                xhr.send(post);
        }