2695-ArrayWrapper.js

// 2695. Array Wrapper
// 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

/**
 * @param {number[]} nums
 * @return {void}
 */
var ArrayWrapper = function(nums) {
    this.data = nums;
};

/**
 * @return {number}
 */
ArrayWrapper.prototype.valueOf = function() {
    // let res = 0;
    // // 累加起来返回
    // for(let i in this.data) {
    //     res += this.data[i];
    // }
    // return res;
    return this.data.reduce((a, b) => a + b, 0);
}

/**
 * @return {string}
 */
ArrayWrapper.prototype.toString = function() {
    // let res = [];
    // for(let i in this.data) {
    //     res.push(this.data[i]);
    // }
    // return "[" + res.join(",") + "]";
    return JSON.stringify(this.data);
}

/**
 * const obj1 = new ArrayWrapper([1,2]);
 * const obj2 = new ArrayWrapper([3,4]);
 * obj1 + obj2; // 10
 * String(obj1); // "[1,2]"
 * String(obj2); // "[3,4]"
 */

const obj1 = new ArrayWrapper([1,2]);
const obj2 = new ArrayWrapper([3,4]);
console.log(obj1 + obj2); // 10
console.log(String(obj1)); // "[1,2]"
console.log(String(obj2)); // "[3,4]"