# Create an array and fill it at the same time in JavaScript

To create an array and fill it at the same time we'll create an **Array instance** and then we'll use the **fill() method**.

For example:

```plaintext
const myNumbers = Array(4).fill(0) // [ 0, 0, 0, 0 ]
```

We place as a parameter to fill() the value we want to place inside the array.

## Extra thing!

Another thing we can use about the fill() method is **substitute some values of the array with the value we want**.

If we have this array:

```plaintext
let myNumbers = [ 1, 2, 3, 4 ]
```

We can use the fill() method to indicate:

1. With which value to fill the array
    
2. Start of the filling
    
3. End of the filling
    

We can fill the myNumbers array with the 0 number starting at the array position 2 and ending at the position 4, so the values 3 and 4 will be replaced by the zeros:

```plaintext
let myNumbers = [ 1, 2, 3, 4 ]

myNumbers.fill(0,2,4) // [ 1, 2, 0, 0 ]
```

The fill() method itself won't create new positions and values in the array, **it will simply replace them**.