# How to check if a value is an object in JavaScript

By Atta Ur Rehman Shah (https://attacomsian.com/about). Published Jul 11, 2020, updated Sep 18, 2022. Topics: JavaScript.
Canonical URL: https://attacomsian.com/blog/javascript-check-variable-is-object

> Learn how to use the Object.prototype.toString() method to check if a value is an object in JavaScript.

In an [earlier article](https://attacomsian.com/blog/javascript-check-if-object-is-array), we looked at different ways to find out if an object is an array in JavaScript. Today, you'll learn how to check if a variable is an object.

We can not use the `typeof` operator as it returns `object` for both arrays and objects in JavaScript. This is because the arrays are internally treated as objects in JavaScript:

```javascript
const fruits = ['Apple', 'Mango', 'Banana']

const user = {
  name: 'John Doe',
  age: 12
}

typeof fruits // object

typeof user // object
```

Unlike `Array.isArray()` method which we used for checking if a variable is an array, there is no `Object.isObject()` method in JavaScript.

The quickest and most accurate way to check if a variable is an object is by using the `Object.prototype.toString()` method. 

This method is part of `Object`'s [prototype](https://attacomsian.com/blog/objects-prototypes-classes-javascript#prototypes) and returns a string representing the object:

```javascript
Object.prototype.toString.call(fruits) // [object Array]

Object.prototype.toString.call(user) // [object Object]
```

As you can see above, the `toString()` method returns `[object Object]` for an object. This is what we want. Now we can be sure that we are dealing with an object and not an array.

Let us write our own `isObject()` method by using the above trick to check if a value is a plain object or not:

```javascript
const isObject = obj => {
  return Object.prototype.toString.call(obj) === '[object Object]'
}

isObject([3, 4, 6])             // false

isObject({})                    // true
isObject({ apple: '?' })       // true

isObject('John Doe')            // false
isObject(true)                  // false
isObject(45)                    // false
```

An alternate approach is to use the `typeof` operator with the `Array.isArray()` method to check if a value is an object:

```javascript
const isObject = obj => {
  return typeof obj === 'object' && obj !== null && !Array.isArray(obj)
}
```

To check if a value is an object, the above `isObject()` method does the following:

1. Use the `typeof` operator to verify that the variable type is `object` — `typeof obj === 'object'`.
2. Verify the value is not `null` — `obj !== null`.
3. Use the `Array.isArray()` method to verify that the value is not an array — `!Array.isArray(obj)`.

The last two steps are necessary to verify a value is an object because the type of `null` and an array is also `object`.

Read [this article](https://attacomsian.com/blog/objects-prototypes-classes-javascript) to learn more about JavaScript objects, prototypes, and classes.