How to compare two arrays - JavaScript

In this article we will learn how to compare two arrays in JavaScript.

It is very common to compare two arrays in JavaScript in JavaScript.

Problem

Now we have a problem which is that we want to compare two arrays.

And we will create a function, if the two arrays are equals, it returns true, and if they are not, it returns false.

Imagine we have two arrays like this:

const array1 = [1, 2, 3, 4];
const array2 = [1, 2, 3, 4, 5];

Are they equals? The answer is no, so the result will be false

false

How to make a function that solves this problem?

The solution to this problem is easy, and fortunately there is already a built-in function that we can use to solve this problem, which is every.

Compare two arrays using every method

We can use every method to compare two arrays.

Let's see an example

function areEquals(array1, array2) {
    if (array1.length === array2.length) {
        return array1.every((value, index) => array2[index] == array1[index]);
    }
    return false;
}

console.log(areEquals([1, 2, 3, 4], [1, 2, 3, 4, 5]));
console.log(areEquals([1, 2, 3, 4], [1, 2, 3, 4]));

Output

false
true

The every() method tests whether all elements in the array pass the test implemented by the provided function. It returns a Boolean value. MDN

Compare two arrays using JSON.stringify()

We can use JSON,stringify() to convert array to a string and compare it.

Let's see an example

// Arrays
const array1 = [1, 2, 3, 4];
const array2 = [1, 2, 3, 4, 5];
const array3 = [1, 2, 3, 4];

// Compare
JSON.stringify(array1) == JSON.stringify(array2);
JSON.stringify(array1) == JSON.stringify(array3);

Output

false
true

Thank you for reading

Thank you for reading my blog. 🚀