Shuffle an Array

Problem statement

Given an integer array nums, design an algorithm to randomly shuffle the array. All permutations of the array should be equally likely as a result of the shuffling.

Implement the Solution class:

• Solution(int[] nums) Initializes the object with the integer array nums.
• int[] reset() Resets the array to its original configuration and returns it.
• int[] shuffle() Returns a random shuffling of the array.

Example 1:

Input["Solution", "shuffle", "reset", "shuffle"][[[1, 2, 3]], [], [], []]Output[null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]ExplanationSolution solution = new Solution([1, 2, 3]);solution.shuffle();    // Shuffle the array [1,2,3] and return its result.                       // Any permutation of [1,2,3] must be equally likely to be returned.                       // Example: return [3, 1, 2]solution.reset();      // Resets the array back to its original configuration [1,2,3]. Return [1, 2, 3]solution.shuffle();    // Returns the random shuffling of array [1,2,3]. Example: return [1, 3, 2]

Constraints:

• 1 <= nums.length <= 200
• -106 <= nums[i] <= 106
• All the elements of nums are unique.
• At most 5 * 104 calls in total will be made to reset and shuffle.

My solution

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

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

/**
 * Returns a random shuffling of the array.
 * @return {number[]}
 */
Solution.prototype.shuffle = function() {
    const currentArr = [...this.nums];
    for (let i = 0, j = currentArr.length; i < currentArr.length, i < j; i++) {
        const idx = Math.floor(Math.random() * j)
        // console.log(idx)
        const tmp = currentArr[idx];
        currentArr[idx] = currentArr[i]
        currentArr[i] = tmp;
        // [currentArr[idx], currentArr[i]] = [currentArr[i], currentArr[idx]]
    }
    
    this.nums = [...currentArr]
    return this.nums;
};

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