How to Use array.at() in JavaScript: Syntax and Examples

The array.at(index) method in JavaScript returns the element at the given index. It supports negative indices to count from the end, making it easier to access elements like the last item with array.at(-1).

Syntax

The array.at(index) method takes one argument:

• index: A number representing the position of the element to retrieve. Positive numbers count from the start (0-based), and negative numbers count from the end (-1 is the last element).

This method returns the element at the specified position or undefined if the index is out of range.

javascript

array.at(index)

Example

This example shows how to use array.at() to get elements by positive and negative indices.

javascript

const fruits = ['apple', 'banana', 'cherry', 'date'];

console.log(fruits.at(1));   // banana
console.log(fruits.at(-1));  // date
console.log(fruits.at(10));  // undefined

Output

banana
date
undefined

Common Pitfalls

Common mistakes when using array.at() include:

• Using negative indices with older methods like array[index], which do not support negatives.
• Expecting array.at() to modify the array (it only reads elements).
• Not handling undefined when the index is out of range.

Always check if the returned value is undefined before using it.

javascript

const numbers = [10, 20, 30];

// Wrong: negative index with bracket notation
console.log(numbers[-1]); // undefined (does NOT get last element)

// Right: use .at() for negative index
console.log(numbers.at(-1)); // 30

Output

undefined
30

Quick Reference

Feature	Description
Parameter	A single integer index (positive or negative)
Positive index	Counts from start (0 is first element)
Negative index	Counts from end (-1 is last element)
Return value	Element at index or undefined if out of range
Supported since	ECMAScript 2022 (ES13)

Key Takeaways

Use array.at(index) to access elements by positive or negative index safely.

Negative indices count from the end, making it easy to get last elements like array.at(-1).

Bracket notation array[index] does not support negative indices.

Always check for undefined when the index might be out of range.

The at() method is part of modern JavaScript (ES2022) and improves code readability.