Array Wrapper

Create a class ArrayWrapper that accepts an array of integers in it's 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

解法:

這是在講他會給這個類別建構時，提供一個數組陣列，他要求你實作兩個function

1. valueOf => 得到當前數組的加總，使用reduce來實作

2. toString => 當前數組轉成文字，直接使用轉JSON方式處理

class ArrayWrapper {
    private _nums: number[];
	constructor(nums: number[]) {
        this._nums = nums;
    }

	valueOf() {
        return this._nums.reduce((pre, cur)=> pre + cur, 0);
    }

	toString() {
        return JSON.stringify(this._nums);
    }
};