function UserAgent() {
  var b=navigator.appName.toUpperCase();
  if (b=="NETSCAPE") this.b="ns";
  else if (b=="MICROSOFT INTERNET EXPLORER") this.b="ie";
  else if (b=="OPERA") this.b="op";
  else this.b=b;

  this.version=navigator.appVersion;
  this.v=parseInt(this.version);

  this.ns=(this.b=="ns" && this.v>=4);
  this.ns4=(this.b=="ns" && this.v==4);
  this.ns5=(this.b=="ns" && this.v==5);
  var AGENTE =navigator.userAgent;
  this.ns6=(AGENTE.indexOf('Netscape6') != -1);

  this.ie=(this.b=="ie" && this.v>=4);
  this.ie4=(this.version.indexOf('MSIE 4')>0);
  this.ie5=(this.version.indexOf('MSIE 5')>0);
  this.ie55=(this.version.indexOf('MSIE 5.5')>0);
  this.ie6=(this.version.indexOf('MSIE 6')>0);


  this.op = (this.b=="op");
  this.op4 = (this.b=="op" && this.v==4);
  this.op5 = (this.b=="op" && this.v==5);
//  this.ecmas= (this.op || this.ie || this.ns6)
this.ecmas=true;
}

at=new UserAgent();