How Do I Check if a Variable Is an Array in JavaScript?

There are several methods to check if a variable is an array or not. In this article, we will explore all methods with code examples and explanations.

1. Using Array.isArray() Method

The basic method to check if a variable is an array or not is by using the Array.isArray() method. It is a built-in JavaScript method used to check the variable is an array or not.

let arr = [10, 20, 30, 40, 50];
let num = 42;

console.log(Array.isArray(arr)); // Output: true
console.log(Array.isArray(num)); // Output: false

2. Using instanceof Array

The instanceof operator is used to check whether a variable is an instance of a specific constructor or not (in this case, it will be Array).

let arr = [10, 20, 30, 40, 50];
let obj = {};

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

3. Checking the Constructor Property

You can also check the constructor property of a variable to check the given variable is an Array or not.

let arr = [10, 20, 30, 40, 50];
let obj = {};

console.log(arr.constructor === Array); // Output: true
console.log(obj.constructor === Array);    // Output: false