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 … ...

Over the years, multiple studies have found that Google Chrome’s V8 JavaScript engine was returning not-so-random numbers when you called the Math.random() function. Today that’s been fixed ...

So it turns out the random number generator long used by developers working with Google's V8 JavaScript engine doesn't really generate random numbers at all.