How to Compare Two Arrays in Javascript

I recently came across a situation where I needed to compare two arrays in Javascript. I was confused why my comparison returned false, so I created a quick console log test.

console.log([0] === [0]) // false

I struggled to understand this for a moment. I remembered that almost everything in Javascript is a function or an object and an array is just an object which inherits from Array with some special methods.

There isn't an 'equal' method for Javascript arrays. I'll do a separate post on this.

We can compare two arrays in Javascript by converting them to strings.

console.log(JSON.stringify([0]) === JSON.stringify([0])) // true

This works for a basic example. What if the items in the array are in a different order?

a = ['test', 'test2', 'test3']
b = ['test', 'test3', 'test2']

console.log(JSON.stringify(a) === JSON.stringify(b)) // false

We'll have to sort them both before converting them to strings.

a = ['test', 'test2', 'test3']
b = ['test', 'test3', 'test2']

console.log(JSON.stringify(a.sort()) === JSON.stringify(b.sort())) // true

Let's make this more useable.

a = ['test', 'test2', 'test3']
b = ['test', 'test3', 'test2']

const equal = (a, b) => {
    return JSON.stringify(a.sort()) === JSON.stringify(b.sort())
}

console.log(equal(a, b))

Some things in Javascript aren't as easy as you'd expect. Now you know how to compare two arrays in Javascript.