2727-Is-Object-Empty.js

/*
https://leetcode.com/problems/is-object-empty/description/

Easy

Given an object or an array, return if it is empty.

    An empty object contains no key-value pairs.
    An empty array contains no elements.

You may assume the object or array is the output of JSON.parse.

 

Example 1:

Input: obj = {"x": 5, "y": 42}
Output: false
Explanation: The object has 2 key-value pairs so it is not empty.

Example 2:

Input: obj = {}
Output: true
Explanation: The object doesn't have any key-value pairs so it is empty.

Example 3:

Input: obj = [null, false, 0]
Output: false
Explanation: The array has 3 elements so it is not empty.

Constraints:

    obj is a valid JSON object or array
    2 <= JSON.stringify(obj).length <= 105

 
Can you solve it in O(1) time?

Runtime 47ms Beats84.77%of users with JavaScript
Memory 48.93MB Beats30.90%of users with JavaScript
*/

/**
 * @param {Object|Array} obj
 * @return {boolean}
 */
var isEmpty = function(obj) {
    if(Array.isArray(obj))
        return obj.length == 0;
    return Object.keys(obj).length == 0;
};