There are two way to check.first is you can directly check whether key contain A or not in binding like this:-. but i think this is not the better way so instead of this you can use ko.computed to check.
Check for operating system information in Windows 7. 1  Click the Start button , enter Computer in the search box, right-click Computer, and then click Properties. 2  Look under Windows edition for the version and edition of Windows that your PC is running.
The Windows 10 edition you have installed, as well as the system type (64-bit or 32-bit), can all be found listed in the System applet in Control Panel. Windows 10 is the name given to Windows version 10.0 and is the latest version of Windows. If you just got a new computer, there's a 99% chance you have Windows 10 installed. (Maybe closer to 99.9%!) Windows 9 never did exist.