The Old way of accessing elements in an array

The usual way to access an element from an array is like this

let arr = [1,2,3,4,5]
let num = arr[1]
num  //2

With this method, we cannot access the elements with the negative Index like

let arr = [1,2,3,4,5]
let num = arr[-1]
num //undefined

If we try with a negative index like arr[-1] or arr[-2] it returns undefined that's where Array.prototype.at() method comes in.

Array.prototype.at()

The at() method takes an integer value and returns the item at that index, allowing for positive and negative integers.

Example

let arr = [1,2,3,4,5]
let num = arr.at[-1]
num  //5

Before we can access the last element of the array using arr[arr.length-1]. But with this array.at() method we can access elements with a negative index easily.

        //0,1,2,3,4 => positive index
let arr =[1,2,3,4,5]
       //-5,-4,-3,-2,-1  => negative index

But there is no browser support yet for this method

Reference MDN article