IE9 equivalent of querySelectorAll

Question

I haven\'t had any problems in FF or Chrome, but IE9 chucks an error on this method. I thought I would be able to use it, due to it having been shown to be supported here:

Answer 1

Running quirksmode is like running non-standard IE6.

You must, must, must(!) have a doctype on top of each HTML page:
Every relevant (and many irrelevant) browser supports it.
And without it... ...well... quirksmode...

You don't want to be running in quirksmode for anything, ever, as you never know what kind of JS/CSS/html5 support is suddenly going to disappear or act weird...

So don't do it.