# How to check if a key exists in a JavaScript object

> Learn how to check if a key exists in a JavaScript object using the in operator or hasOwnProperty(), and how they differ when properties are inherited.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-05-31 | Topics: [JavaScript](https://flaviocopes.com/tags/js/) | Canonical: https://flaviocopes.com/how-to-check-key-exists-javascript/

Given a [JavaScript](https://flaviocopes.com/javascript/) object, you can check if a property key exists inside its properties using the `in` operator.

Say you have a `car` object:

```js
const car = {
  color: 'blue'
}
```

We can check if the `color` property exists using this statement, that results to `true`:

```js
'color' in car
```

We can use this in a conditional:

```js
if ('color' in car) {

}
``` 

Another way is to use the `hasOwnProperty()` method of the object:

```js
car.hasOwnProperty('color')
```

When inheritance is an important part of your applications structure, the difference is that `in` will result `true` even for properties inherited by parent objects. `hasOwnProperty()` doesn't. It will only return `true` if the object has that property directly - not one of its ancestors.

I use a fallback mechanism when I want one property and fallback to a default value if that does not exist:

```js
car.brand || 'Ford'
```

If the `brand` property key does not exist on the object, this statement results to the `Ford` string.