How to Check if Array is Empty in JavaScript: Simple Guide

To check if an array is empty in JavaScript, use the length property and compare it to zero, like array.length === 0. If the length is zero, the array has no elements and is empty.

Syntax

Use the length property of an array to find out how many elements it contains. If the length is zero, the array is empty.

• array.length: Returns the number of elements in the array.
• Check if array.length === 0 to confirm emptiness.

javascript

if (array.length === 0) {
  // array is empty
}

Example

This example shows how to check if an array is empty and print a message accordingly.

javascript

const fruits = [];

if (fruits.length === 0) {
  console.log('The array is empty');
} else {
  console.log('The array has elements');
}

Output

The array is empty

Common Pitfalls

Some common mistakes when checking if an array is empty include:

• Using array == null or array === null which only checks if the array variable is null or undefined, not if it has elements.
• Checking if the array itself is truthy or falsy, which is always true for arrays even if empty.

Always check the length property to determine emptiness.

javascript

const arr = [];

// Wrong way:
if (!arr) {
  console.log('Array is empty'); // This will NOT run because arr is truthy
}

// Right way:
if (arr.length === 0) {
  console.log('Array is empty');
}

Output

Array is empty

Quick Reference

Summary tips for checking if an array is empty:

• Use array.length === 0 for a clear and reliable check.
• Do not check the array variable itself for truthiness or null.
• Remember that an empty array is still an object and truthy in JavaScript.

Key Takeaways

Check if an array is empty by testing if array.length === 0.

Never rely on truthy or falsy checks to determine if an array is empty.

An empty array is still truthy in JavaScript, so always use the length property.

Avoid checking if the array variable is null or undefined to test emptiness.

Using length is the simplest and most reliable method.