How does Math.random() work in JS?

While researching random number generation using quantum programming, I wondered how Math.random() works in JS.

Here are a few points to highlight:

1. Math.random() is part of the browser API, not the language itself.

2. In all browsers after 2015, Math.random() uses the pseudorandom number generation algorithm xorshift128+.

3. xorshift128+ uses a seed phrase to set the initial values of state0 and state1. You can see the algorithm code below:

uint32_t state0 = 1;
uint32_t state1 = 2;
uint32_t mwc1616() {
  state0 = 18030 * (state0 & 0xFFFF) + (state0 >> 16);
  state1 = 30903 * (state1 & 0xFFFF) + (state1 >> 16);
  return state0 << 16 + (state1 & 0xFFFF);
}

4. For Node.js, you can specify the seed phrase at startup using the parameter —random_seed. If you start Node with this parameter and generate a number twice, the result will be the same. The code for the calls is below:

$ node --random_seed=42
Welcome to Node.js v16.0.0-pre.
Type ".help" for more information.
> Math.random()
0.7939112874678715
> for (let i = 0; i < 1000; i++) Math.random();
0.6681221903420669
> Math.random()
0.009229884165582902
>
$ node --random_seed=42
Welcome to Node.js v16.0.0-pre.
Type ".help" for more information.
> Math.random()
0.7939112874678715
> for (let i = 0; i < 1000; i++) Math.random();
0.6681221903420669
> Math.random()
0.009229884165582902

Some links:

Article: https://apechkurov.medium.com/v8-deep-dives-random-thoughts-on-math-random-fb155075e9e5 V8 blog post: https://v8.dev/blog/math-random

If you're interested in reading about random number generation through quantum programming, please let me know in the comments.