Originally Posted by AndrewGSW
It doesn't really require an IE8 conditional though, does it? Because it starts with:
no, i'm sure hes talking about the common <head> scripts you see on most professional sites and integrated into modern frameworks like bootstrap or boilerplate.
it's an IE shim for new  methods, Object.[keys,defineProperty, etc], Date.now, et al.
only IE would load the shim as its a sync external script tag in the head behind a conditional comment.
so, if you have a solid foundation, you can simply write the 21st-century version and not have to worry about old browsers; they will run the new code just like real browsers.
or you can write expressly for obsolete browsers and make it harder on yourself to save a few KB that only ancient devices will ever fetch anyway...
BROWSER STATS [% share]
(2013/10/31) IE7:0.5, IE8:8.6, IE9:5.3, IE10:12.3, FF:17.7, CH:41.8, SF:8.1, MOBILE:20.4