function loadScript(url) {
  if (!this.loadedScript) {
    this.loadedScript = new Array();
  }
  if (this.loadedScript.indexOf(url) == -1) {
    this.loadedScript.push(url);
    var e = document.createElement("script");
    e.src = url;
    e.type = "text/javascript";
    document.getElementsByTagName("head")[0].appendChild(e);
  } 
}