Is Object Empty - Practice Coding Problems

Is Object Empty - Problem

JavaScript Easy

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

Definition of 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.

Input & Output

Example 1 — Empty Object

$ Input: obj = {}

› Output: true

💡 Note: The object has no key-value pairs, so it's empty and we return true

Example 2 — Non-empty Array

$ Input: obj = [null, false, 0]

› Output: false

💡 Note: The array contains elements (even though they're falsy values), so it's not empty

Example 3 — Empty Array

$ Input: obj = []

› Output: true

💡 Note: The array contains no elements, so it's empty and we return true

Constraints

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

Visualization

Tap to expand

Understanding the Visualization

Input

Object or array from JSON.parse

Check

Determine if container has any items

Output

Return boolean true/false

Key Takeaway

🎯 Key Insight: Use built-in size methods to efficiently check if containers are empty

Asked in

G Google 15 M Microsoft 12 a Amazon 8

The key insight is to use built-in methods like Object.keys().length for objects and array.length for arrays. Best approach uses native size checking. Time: O(n), Space: O(1)

Common Approaches

Approach	Time	Space	Notes
✓ Built-in Methods	O(n)	O(1)	Use Object.keys().length for objects and array.length for arrays
Iteration Check	O(1)	O(1)	Iterate through all properties/elements to see if any exist

Built-in Methods — Algorithm Steps

Step 1: Check if input is array or object
Step 2: Use appropriate built-in method
Step 3: Compare length/count to zero

Visualization

Tap to expand

Step-by-Step Walkthrough

Type Check

Determine if array or object

Size Method

Call appropriate length/keys method

Compare Zero

Return true if size equals 0

Code -

solution.c — C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int solution(char* jsonStr) {
    int len = strlen(jsonStr);
    if (jsonStr[0] == '[') {
        return len == 2 && jsonStr[1] == ']';
    } else {
        return len == 2 && jsonStr[1] == '}';
    }
}

int main() {
    char input[1000];
    fgets(input, sizeof(input), stdin);
    input[strcspn(input, "\n")] = 0;
    
    int result = solution(input);
    printf(result ? "true\n" : "false\n");
    
    return 0;
}

Time & Space Complexity

Time Complexity

⏱️

O(n)

Object.keys() must enumerate all properties, but very fast native implementation

✓ Linear Growth

Space Complexity

O(1)

Only uses constant extra space for the length check

✓ Linear Space

35.7K Views

Medium Frequency

~5 min Avg. Time

892 Likes

Ln 1, Col 1

Smart Actions

💡 Explanation

AI Ready

💡 Suggestion Tab to accept Esc to dismiss

// Output will appear here after running code

Code Editor Closed

Click the red button to reopen

Input & Output

Constraints

Visualization

Related Problems

Common Approaches

Built-in Methods — Algorithm Steps

Visualization

Code -

Time & Space Complexity

Select Compiler