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 … ...

In most implementations if not in all, Math.random's generator is silently seeded at startup by some supposedly random value, usually the present time to the millisecond or whatever other granularity ...

Calling Alea (or any of the others) with new is unnecessary, but harmless. The optional arguments may be of any number and nature. The call returns a function, random, that is functionally equivalent ...

And they don't say the random number generator function in JavaScript -- Math.random() -- is broken. They say it "offers sub-par quality." Specifically, V8 used a pseudorandom number generator (PRNG) ...

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 ...

Random number generation: ... Called The Central Randomizer, it was used in JavaScript 1.0. After this, a huge variety of true RNGs were developed, ...