Problem

Create a class ArrayWrapper that accepts an array of integers in its constructor. This class should have two features:

When two instances of this class are added together with the + operator, the resulting value is the sum of all the elements in both arrays. When the String() function is called on the instance, it will return a comma separated string surrounded by brackets. For example, [1,2,3].

Example 1:

Input: nums = [[1,2],[3,4]], operation = “Add” Output: 10 Explanation: const obj1 = new ArrayWrapper([1,2]); const obj2 = new ArrayWrapper([3,4]); obj1 + obj2; // 10

Example 2:

Input: nums = [[23,98,42,70]], operation = “String” Output: “[23,98,42,70]” Explanation: const obj = new ArrayWrapper([23,98,42,70]); String(obj); // “[23,98,42,70]”

Example 3:

Input: nums = [[],[]], operation = “Add” Output: 0 Explanation: const obj1 = new ArrayWrapper([]); const obj2 = new ArrayWrapper([]); obj1 + obj2; // 0

Constraints:

0 <= nums.length <= 1000 0 <= nums[i] <= 1000 Note: nums is the array passed to the constructor

Pre analysis

Looks straighforward problem, just need to override valueOf and toString method

Another solution

– without using inbuild methods

class ArrayWrapper {
  constructor(nums) {
    this.nums = nums;
  }

  valueOf() {
    let sum = 0;
    for (let i = 0; i < this.nums.length; i++) {
      sum += this.nums[i];
    }
    return sum;
  }

  toString() {
    let str = '[';
    for (let i = 0; i < this.nums.length; i++) {
      str += this.nums[i];
      if (i !== this.nums.length - 1) {
        str += ',';
      }
    }
    str += ']';
    return str;
  }
}```