If anyone wants a seedable, and therefore deterministic PRNG, use the seedrandom package https://www.npmjs.com/package/seedrandom

  // Global PRNG: set Math.random.
  seedrandom('hello.', { global: true });
  console.log(Math.random());          // Always 0.9282578795792454

I found this useful when using worker threads to 'render' a construction by slices that included some randomness (that should be the same for each thread)