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 … ...

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.

There’s no cheating this random number generator The protocol ensures jury duty selections and other draws are truly random and secure ...

That’s exactly how the world’s only commercially available quantum random number generator works. But its speed is limited to about one megabit per second.