Advent
The good thing about this time of year is advent: a time when people do something every day from 1st to 24th or 25th December. And it's the same with coding challenges: you get one per day for 24/25 days.
Here are a few that I'm doing this year/have done in the past/will do in the future. It's not too late to start any of these! You might just have to do more than one a day to catch up, or just skip the first few.
Advent of Code
This is one that can be done in any language. It's also not easy. I started this last year, but only did a few days before the difficulty level rose above the amount of time I had available.
Scrimba's JavaScriptmas
You have to sign up for a Scrimba account for this, but it's free. It's JavaScript challenges which start really easy and get harder. But they have additional challenges if it's too easy. And you can change the CSS too. I am doing it this year and enjoying it - it helps that if I have time I can do the additional challenges and if I don't I can just do the basic challenge.
Advent of CSS / Advent of JS
I've lumped these together because they're from the same people. You get a Figma design (for the CSS challenge) and instructions on what you should do. You can do just the CSS or just the JS, but both feels more satisfying. I haven't started this because I just don't have the time yet, but it looks fun, so I've been saving the files and will do them when things have quietened down - maybe one a weekend.
Any more?
Anyone know of any more coding advent challenges?