Functional RNG in Javascript using LCG like Java's Random

random.js

function* Random(random) {
    const m = [0xe66d, 0xdeec, 0x005];

    let seed = [
        ((random) & 0xffff)         ^ m[0],
        ((random / 2**16) & 0xffff) ^ m[1],
        ((random / 2**32) & 0xffff) ^ m[2]
    ];

    function next(bits) {
        let carry = 0xb;
        let r = [];
        r[0] = (seed[0] * m[0]) + carry;
        carry = r[0] >>> 16;
        r[0] &= 0xffff;
        r[1] = (seed[1] * m[0] + seed[0] * m[1]) + carry;
        carry = r[1] >>> 16;
        r[1] &= 0xffff;
        r[2] = (seed[2] * m[0] + seed[1] * m[1] + seed[0] * m[2]) + carry;
        r[2] &= 0xffff;
        seed = r;
        return (seed[2] * 2**16 + seed[1]) >>> (32 - bits);
    }

    while (true) {
        yield (2**27 * next(26) + next(27)) / 2**53;
    }
};

The LCG parameter 0x5DEECE66D used in Java is a composite 7 x 443 x 739 x 11003 = 25214903917 passing the Marsaglia's diehard test.

Basic usage:

const random = Random(123);
console.log(random.next()); // 0.7231742029971469
console.log(random.next()); // 0.9908988967772393
console.log(random.next()); // 0.25329310557439133

Advanced usage (using Immutable):

const { Seq } = require("immutable");

const random = Random(123);
const ten = Seq(random).take(10);
console.log(ten.toArray());