internet explorer 8 - How can I detect if my app runs under IE8 vs IE9 in JavaScript? -

i have piece of functionality needs differ between ie8 , ie9 (ie9 uses nice library main code path, slight minority of users of app still on ie8 library breaks under. need gracefully degrade less-nice library them).

what best way distinguish ie8 ie9?

if possible, i'd version of answer treats ie9 ie8 compatibility turned on ie8; , 1 treats ie9.

there's 0 need detect other browsers or ie versions - locked down corporate environment there's no risk of needing detect beyond 2.

conditional comments. there other alternatives conditional comments simple , functional. msft provides information http://msdn.microsoft.com/en-us/library/ms537509(v=vs.85).aspx