var version = parseInt(navigator.appVersion) 
  // Returns 4 for 4.x browsers
  

  var isIE = navigator.appVersion.indexOf("MSIE")>0
  var isNav = navigator.appVersion.indexOf("Nav")>0

  // Is it IE or Nav and atleast version 4.0
  var isIE4 = isIE && version>=4  
  var isNav4 = isNav && version>=4
  
  // Is the all collection supported
 // supportAll assigned true if supported
 // else assigned false
  var supportAll = (document.all != null)