code: function loadScript(uri, callback) {
    var elem = document.createElement("script");
    elem.charset = "utf-8";
    elem.src = uri;
    elem.onreadystatechange = elem.onload = function() {
      if (!this.readyState || readyStateValue[this.readyState]) {
        elem.onreadystatechange = elem.onload = null;
        if (typeof callback === "function") {
          callback();
        }
      }
    };
    elem.onerror = function() {
      if (console && typeof console.error == "function")
        console.error("Cannot load script " + uri);
      callback && callback("Cannot load script " + uri);
    }
  
    if (qx.$$loader.isLoadParallel) {
      elem.async = null;
    }
  
    var head = document.getElementsByTagName("head")[0];
    head.appendChild(elem);
  }
docs: /*
  Load Javascript