How to check if a variable is an array in JavaScript

If you try to apply the typeof operator to a JavaScript array, you won’t be able to tell if it’s an array. To check if a variable is an array in JS, you need to take a different approach.

All JavaScript arrays are objects.

const arr = [1, 2, 3];
const obj = {};

console.log(typeof arr); // object
console.log(typeof obj); // object

You can use the built-in function Array.isArray to check if a JS variable is an array.

const arr = [1, 2, 3];
const obj = {};

console.log(Array.isArray(arr)); // true
console.log(Array.isArray(obj)); // false

An alternative would be to use the instanceof operator.

const arr = [1, 2, 3];
const obj = {};

console.log(arr instanceof Array); // true
console.log(obj instanceof Array); // false