# The JavaScript super keyword

> Learn what the super keyword does in JavaScript classes, how it calls the parent class constructor when you extend a class, and where you can use it.

Author: [Flavio Copes](https://flaviocopes.com/about/) | Published: 2020-06-25 | Topics: [JavaScript](https://flaviocopes.com/tags/js/) | Canonical: https://flaviocopes.com/javascript-super/

When we work with classes in [JavaScript](https://flaviocopes.com/javascript/), it's common to use the `super` keyword.

In this post I want to clarify what's it useful for.

Suppose you have a class `Car`:

```js
class Car {

}
```

and in this class we have a `constructor()` method:

```js
class Car {
  constructor() {
    console.log('This is a car')
  }
}
```

The constructor method is special because it is executed when the class is instantiated:

```js
const myCar = new Car() //'This is a car'
```

You can have a `Tesla` class that extends the `Car` class:

```js
class Tesla extends Car {

}
```

The `Tesla` class inherited all the methods and properties of `Car`, including the `constructor` method.

We can create an instance of the `Tesla` class, creating a new `myCar` object:

```js
const myCar = new Tesla()
```

And the original constructor in `Car` is still executed, because `Tesla` does not have one of its own.

We can override the `constructor()` method in the `Tesla` class:

```js
class Tesla extends Car {
  constructor() {
    console.log('This is a Tesla')
  }
}
```

and 

```js
const myCar = new Tesla()
```

will print `This is a Tesla `.

In the `constructor()` method we can also call `super()` to invoke the same method in the parent class:

```js
class Tesla extends Car {
  constructor() {
    super()
    console.log('This is a Tesla')
  }
}
```

Calling 

```js
const myCar = new Tesla()
```

will now execute 2 console logs. First the one defined in the Car class constructor, the second the one defined in the Tesla class constructor:

```
'This is a car'
'This is a Tesla'
```

Note that `super()` can only be called in the constructor, not in other methods.

And we can pass in any parameter, if the constructor accepts parameters.