You can see a video of the Cloudflare lava wall by [Tom Scott], below. If you don’t need a random number generator, maybe you could use a spectrum analyzer. Thanks to [Ptkwilliams] for the tip.

According to this post on the official V8 Javascript blog, the pseudo-random number generator (PRNG) that V8 Javascript uses in Math.random() is horribly flawed and getting replaced with something ...