My Javascript console is acting INSANE

I promise I wanted a more descriptive title but I don't even know how to describe what's happening. Every keystroke is behaving bizzarely. Extra tabs get inserted, the cursor doubles back on itself, I legit can't type anything. I'm having to type my code out separately and paste it in. Can't edit anything in the console itself. Here's a screenshot. Tried to type a function call addLineItem(); and this is what I got.