Check if a variable is an array in JavaScript

By Thomas Taylor | April 01, 2023 | 1 minutes

In TypeScript or JavaScript, checking if a variable is an array can be completed in two ways.

Using the `Array.isArray()`

Using the native Array.isArray() method, a boolean will be returned.

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const names = ["sally", "billy", "mary"];
const notAnArray = 'str';
console.log(Array.isArray(names)); // true
console.log(Array.isArray(notAnArray)); // false

Using the `instanceOf` operator

As an alternative option, instanceOf will yield the same results.

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const names = ["sally", "billy", "mary"];
const notAnArray = 'str';
console.log(names instanceof Array); // true
console.log(notAnArray instanceof Array); // false