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 ...

The method used to generate the digits, a pair of 555 timers sending pulses through linear-feedback shift registers, would at best be considered pseudo-random.

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.

Current methods of generating random numbers can produce predictable results. Researchers said the new method could generate higher-quality random numbers with less computer processing.

A team of international scientists has developed a laser that can generate 254 trillion random digits per second, more than a hundred times faster than computer-based random number generators (RNG).