Have you ever thought

I wish I knew when my selector didn't match a goddamn thing. 
There has to be a better way!

oh you didn't?...well you're in luck!

With weaintfoundshit.js™ you'll never have this problem for, uhm, the first time

Fire up the console with Cmd + Opt + i or Ctrl + Shift + i and try fetching a missing selector using something like querySelectorAll and/or jQuery