How to detect Operating System?

(question in title)

how

Do you mean detecting browsers?
Opera:
window.opera
IE:
(some dummy ele).onclick=function(){window.isIE=window.event}
(some dummy ele).click()
window.isIE

no, detecting the device like:
IOS
Andriod
Mac
Windows
ect

You need to change the title to "How to detect Operating System?", because what you listed above are operating systems.

Devices are:

  • smartphone
  • tablet
  • notebook
  • desktop computer

done

navigator.appVersion

whoops