Advent of Code is an Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like. People use them as interview prep, company training, university coursework, practice problems, a speed contest, or to challenge each other.
I am using this as an oppritunity to continue learning Python. I may also have some solutions in vanilla JS just to wrap my head around some of the more difficult problems.