JavaScript Interview Question #38

How can you check whether a value is an array?

Objects, Arrays & Core Data Handling Junior Beginner

Quick Interview Answer

Use Array.isArray(value). It reliably determines whether a value is an Array, including cases where typeof would only report "object".

Detailed Explanation

Use Array.isArray(value). It reliably determines whether a value is an Array, including cases where typeof would only report "object".

Using typeof is insufficient because arrays, plain objects, and null all produce object-related results rather than identifying arrays specifically.

Code Example

const values = [1, 2, 3];
const user = { id: 1 };

console.log(Array.isArray(values)); // true
console.log(Array.isArray(user));   // false
console.log(typeof values);         // "object"