The process to make a raycaster is very unique and instersting. The browser fps are in half so keep that in my mind and the game is not optimized at all (currently running with 330 rays), even has some  bad code just to make it in done and a bit of a fisheye effect. It requires basic knowledge in geometry so keep that in mind. These are some tutorials-videos I followed and you might find useful (1,2,3). In my opinion it's very worth it and looking to make a better one in the future.