# Sparse arrays in JavaScript

If there are gaps in the sequence of keys in the array, then you can get a sparse array. Let's see what it looks like. Let's have some array:

`let arr = ['a', 'b', 'c'];`

Let's add one more element to this array so that the sequence of keys have gaps:

`arr[4] = '!';`

As a result, a "hole", which has the value undefined, appears in the array:

`console.log(arr); // shows ['a', 'b', 'c', undefined, '!']`

The length of the array will consider all holes. That is, in our case, it will be `5`, and not `4`:

`console.log(arr.length); // shows 5`

Find out the length of the next array:

`let arr = []; arr[3] = 'a'; arr[8] = 'b';`
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