function loadScript(sURL, fCallback){
        var elScript = document.createElement("script");
        elScript.type = "text/javascript";
        elScript.async = true;
        elScript.src = sURL;

        // run callback and free memory on load
        var fOnLoad = function(){
            if(typeof fCallback == "function"){
                fCallback();
            }
            document.body.removeChild(elScript);
            elScript = fOnLoad = null;
        };

        // attach onLoad event handler
        if(elScript.addEventListener) { // for FF
            elScript.addEventListener("load", fOnLoad, false);
        } else if(typeof elScript.onload == "undefined"){
            elScript.onreadystatechange = function(){ // for IE
                if(this.readyState === "complete" || this.readyState === "loaded"){
                    fOnLoad();
                }
            };
        } else { // and for other polite browsers
            elScript.onload = fOnLoad;
        }

        document.body.appendChild(elScript);
    }
load JavaScript
@param {String} sURL
@param {Function} fCallback callback function on load