Question

2727. Is Object Empty

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Description

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?

Solutions

Solution 1

function isEmpty(obj: Record<string, any> | any[]): boolean {
  for (const x in obj) {
    return false;
  }
  return true;
}

/**
 * @param {Object | Array} obj
 * @return {boolean}
 */
var isEmpty = function (obj) {
  for (const x in obj) {
    return false;
  }
  return true;
};

Solution 2

function isEmpty(obj: Record<string, any> | any[]): boolean {
  return Object.keys(obj).length === 0;
}