Get the Last Element in an Array in JavaScript
To get the last element in an array, you get the array's .length property and get the element at index length - 1.
const array = ['a', 'b', 'c'];
array.length; // 5
array[array.length - 1]; // 5
JavaScript doesn't throw array out of bounds exceptions, so it is safe to use array[array.length - 1] without checking if array.length === 0.
JavaScript will return undefined if array is empty.
const array = [];
array[array.length - 1]; // undefined
Using slice()
You can also use the slice() function to get the last element in an array.
The slice() method returns a subsection of the array, and supports negative indexes.
That means slice(-1) returns a 1 element array with just the last element in the original array.
const array = [1, 2, 3, 4, 5];
array.slice(-1); // [5]
So to get the last element of an array without referencing the length property using the following:
const lastElement = array.slice(-1)[0]; // 5
You can also use destructuring if you do not wish to use the syntax from above.
const array = [1, 2, 3, 4, 5];
const [last] = array.slice(-1); // returns 5
This approach also returns undefined if array is empty.
const array = [];
const [last] = array.slice(-1); // undefined