var ab = browser(1,2 );
function browser(a,b) {
  if ((navigator.appVersion.substring(0,3) >= a && navigator.appName == 'Netscape' && a != -1) || (navigator.appVersion.substring(0,3) >= b && navigator.appName.substring(0,9) == 'Microsoft' && b != -1))
    return true;	
else return false;
}