How to Divide an Array in Half in JavaScript

Updated onbyAlan Morel
How to Divide an Array in Half in JavaScript

Arrays are ubiquitous in JavaScript because of their ability to hold several items in a single array.

Depending on the circumstances, sometimes you want to divide an array into two halves, usually to perform some kind of operation to each half.

In this post, we'll learn the best way to divide an array into two halves in JavaScript.

How to divide an array into two halves

Before we divide an array in half, let's start with our example array:

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

console.log(array);
(10) [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

To divide it in half, we first need to get the length of the array and then divide it by two. Also, we'll use a ceiling function to round up the result of the division.

That will let us know the midpoint of the array.

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const midpoint = Math.ceil(array.length / 2);

console.log(midpoint);
5

Using this midpoint, we can now get two sections of the array using the slice() function.

const array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

const midpoint = Math.ceil(array.length / 2);

const firstHalf = array.slice(0, midpoint);

const secondHalf = array.slice(-midpoint);

console.log(firstHalf);
console.log(secondHalf);
(5) [1, 2, 3, 4, 5]
(5) [6, 7, 8, 9, 10]

Conclusion

In this post, we learned how to divide an array into two halves in JavaScript.

Simply calculate the midpoint of the array and use the slice() function to get two halves of the array.

Thanks for reading and happy coding!

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