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.
To find out which version of Outlook is installed on your computer, do the following: In Outlook, click File. Click Office Account. If you don't see Office Account, option, click Help. You'll see the product version on the right side of the page. You'll find the version and build number under Product Information.