Solution.js

/**
 * @param {number[]} nums
 */
const Solution = function (nums) {
    this.nums = nums || [];
};

/**
 * Resets the array to its original configuration and return it.
 * @return {number[]}
 */
Solution.prototype.reset = function () {
    return this.nums;
};

/**
 * Returns a random shuffling of the array.
 * @return {number[]}
 */
Solution.prototype.shuffle = function () {
    let a = this.nums.slice();
    for (let i = 0; i < a.length; i++) {
        let rand = Math.floor(Math.random() * (a.length - i)) + i;
        let tmp = a[i];
        a[i] = a[rand];
        a[rand] = tmp;
    }
    return a;
};

/**
 * Your Solution object will be instantiated and called as such:
 * var obj = Object.create(Solution).createNew(nums)
 * var param_1 = obj.reset()
 * var param_2 = obj.shuffle()
 */