Great work! The mechanics were outstanding -- the wall crawl and double jump were very well implemented. The player controller here is very nicely tuned and responsive, which makes the gameplay very fluid. The player animations were also great, and transitioned smoothly and naturally. The map function was very detailed and useful, and you created a large world. It's particularly impressive that this is a solo project written in javascript with no external assets. Nice!
Some feedback that I hope is helpful: it would have been great to have felt more invested in the character or environment, or for there to have been some kind of story or objective (aside from collection/completion). The game did abstract platforming and collecting very well, but in further development, making the world come alive a bit more would be fun, even if it were at the expense of world size. And this may be a matter of personal preference, but I would have loved to have seen more challenge with these great mechanics.
Great game!