Script for JS Injection into Chrome

Hiya folks.

Before anybody gets their knickers in a twist, this post isn’t about being malicious on the web. I simply want to add some functionality to websites that I think forgot about efficient navigation/functionality.

Example: On a carousel of images that I visit often (dating site), I’d like to use my keyboard arrows, which I naturally go to for image carousels. Why they didn’t integrate this, I have no clue. So…

I’m looking to accomplish the following. In Chrome, either through the developer window, place some simple JS. Basically some watchers that operate when left and right arrows trigger advancement on the carousel.

Is there a way to open the developer console (⌘-⌥-J) and paste in some JS somewhere that fits the site dom?

Any insight appreciated.