How to Check the Number of Items in an Array in JavaScript

Check the Number of Items in an Array in JavaScript

Counting how many items are in an array is a basic operation in JavaScript. In this tutorial, we explore the most common and reliable ways to check the number of items in an array.

Using the .length Property

The simplest and most direct method to find out how many elements are in a JavaScript array is to use the built-in length property. Every array in JavaScript keeps track of how many items it holds using this property. No extra work is needed.

const fruits = ["apple", "banana", "cherry"];

console.log(fruits);
console.log("Number of items:", fruits.length);

["apple", "banana", "cherry"]
Number of items: 3

Checking Length of an Empty Array

Sometimes, you want to confirm that an array is empty. The .length property makes this trivial — an empty array will always have a length of 0. This is especially useful in form validation, pagination, or any condition that depends on whether or not data exists.

const tasks = [];

console.log("Task count:", tasks.length);

Task count: 0

sUsing Length with Dynamic Arrays

When arrays change — for example, items are pushed or popped — the length property updates automatically. This makes it reliable in dynamic applications where the contents of an array are not fixed.

let cart = ["Item 1", "Item 2"];

console.log("Initial count:", cart.length);

cart.push("Item 3");

console.log("Final items:", cart);
console.log("Final count:", cart.length);

Initial count: 2
Final items: ["Item 1", "Item 2", "Item 3"]
Final count: 3

When Should You Use Array Length?

Here are a few scenarios where checking the number of items in an array is extremely useful:

• Conditional checks: Only proceed if the array has at least one element.
• Looping: Use array.length in for loops to iterate through items.
• Displaying UI elements: Show or hide sections based on whether an array is empty.
• Input validation: Ensure a user has selected a minimum or maximum number of items.