# Multidimensional arrays in JavaScript

Array elements can be not only strings and numbers, but also arrays. In this case, we get an array of arrays, or a multidimensional array.

In the following example, the array `arr` consists of three elements, which in turn are arrays:

`let arr = [['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i']];`

Let's rewrite in a more understandable way:

`let arr = [ ['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i'], ];`

Depending on the level of nesting, arrays can be two-dimensional - an array of arrays, three-dimensional - an array of arrays of arrays (and so on - four-dimensional, five-dimensional, etc.).

The above array is two-dimensional, since there are other sub-arrays inside one array, and there are no other arrays already in these sub-arrays.

To display any element from a two-dimensional array, you should write not one pair of square brackets, but two:

`let arr = [ ['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i'], ]; console.log(arr[0][1]); // shows 'b' console.log(arr[1][2]); // shows 'f'`

Given the following array:

`let arr = [ ['a', 'b', 'c'], ['d', 'e', 'f'], ['g', 'h', 'i'], ['j', 'k', 'l'], ];`

Use it to output elements with the text `'l'`, `'e'`, `'g'` and `'a'`

Given the following array:

`let arr = [[1, 2], [3, 4], [5, 6]];`

Referring to each array element, find the sum of all its elements.

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