an implementation of the rand() function of TI calculators in javascript

tirand.js

// generate TI random values and seeds
const mod1 = 2147483563;
const mod2 = 2147483399;
const mult1 = 40014;
const mult2 = 40692;

/**
 * Check whether two arrays are equal to each other
 * @param {Array} arr1
 * @param {Array} arr2
 * @return {Boolean}
 */
function checkArrayEquality(arr1, arr2) {
    if (arr1.length !== arr2.length) return false;
    for (let i = 0; i < arr1.length; i++) {
        if (arr1[i] !== arr2[i]) return false;
    }
    return true;
}

/** Random generator class */
class RandomGenerator {
    /**
     * @param {Number[]|Number} seed The seed
     */
    constructor(seed) {
        if (!seed) {
            this.seed = [12345, 67890]; // this is the default seed
        } else if (seed instanceof Array) {
            this.seed = seed;
        } else {
            this.seed = [(mult1 * seed) % mod1, seed % mod2];
        }
    }
    /**
     * Generate a single random value
     * @return {Number}
     */
    generate() {
        this.seed = [(this.seed[0] * mult1) % mod1, (this.seed[1] * mult2) % mod2];
        let result = (this.seed[0] - this.seed[1]) / mod1;
        if (result < 0) result += 1;
        return result;
    }
    /**
     * Generate random integers
     * @param {Number} low Lower limit
     * @param {Number} high Upper limit
     * @param {Number} num Count
     * @return {Number[]}
     */
    genInt(low, high, num = 1) {
        let ret = Array(num).fill(0);
        ret = ret.map(() => {
            let num = this.generate();
            return Math.floor(num * (high - low + 1) + low);
        });
        if (num === 1) return ret[0];
        return ret;
    }
    /**
     * Match an array of random integers
     * @param {Number[]} matchArr Array to match
     * @param {Number} low Lower limit for integers
     * @param {Number} high Upper limit for integers
     * @return {Number} The seed from which the array was generated
     */
    findSeed(matchArr, low, high) {
        // if low/high are defined then it uess genInt otherwise plain generate()
        let arr = [];
        let gen;
        if (!high) gen = this.generate;
        else gen = () => this.genInt(low, high);
        for (;;) {
            if (arr.length >= matchArr.length) arr.shift();
            arr.push(gen());
            console.log('checking', arr, 'against', matchArr);
            if (checkArrayEquality(arr, matchArr)) {
                console.log('found:', this.seed);
                return this.seed;
            }
        }
    }
}

module.exports = RandomGenerator;