Yes, Grade 13 exists. We warned you about this at Orientation.
This grade is a collection of power-ups: features that were added to JavaScript over the last decade to make common tasks shorter, safer and more pleasant. None of them let you do anything you couldn't do before. But they'll make your code cleaner, and, just as importantly, you'll see them everywhere in modern code, tutorials and documentation. If you don't know them, other people's code will look like hieroglyphics.
Let's power up. 🍄