Using the fill method

The fill method fills the array with a value. For example, consider the following array:

let numbersCopy = Array.of(1,2,3,4,5,6); 

The numbersCopy array has the length 6, meaning we have six positions. Let's use the following code:

numbersCopy.fill(0); 

Here, the numbersCopy array will have all its positions with value ([0,0,0,0,0,0]). We can also pass the start index that we want to fill the array with, as follows:

numbersCopy.fill(2, 1); 

In the preceding example, all the positions of the array will have the value 2, starting from position 1 ([0,2,2,2,2,2]).

It is also possible to pass the end index that we want to fill the array with:

numbersCopy.fill(1, 3, 5); 

In the preceding example, we will fill the array with value 1 from index 3 to 5 (not inclusive), resulting in the following array: [0,2,2,1,1,2].

The fill method is great when we want to create an array and initialize its values, as demonstrated:

let ones = Array(6).fill(1); 

The preceding code will create an array of length 6 and all its values as 1 ([1,1,1,1,1,1]).