# reduceRight method

The `reduceRight` method works exactly like `reduce` - see it for a complete understanding. The only difference is that `reduce` iterates from left to right, while `reduceRight` iterates from right to left.

## Syntax

`array.reduceRight(function(intermediate result, element, index, array) { return new intermediate result; }, initial value);`

## Example

Let's find the sum of the array elements:

`let arr = [1, 2, 3, 4, 5, 6]; let res = arr.reduceRight(function(sum, elem) { return sum + elem; }, 0); console.log(res);`

The code execution result:

`21`

## Example

Let's merge a two-dimensional array into a one-dimensional:

`let arr = [['a', 'b'], ['c'], ['d', 'e']]; let res = arr.reduceRight(function(elem1, elem2) { return elem1.concat(elem2); }, []); console.log(res);`

The code execution result:

`['d', 'e', 'c', 'a', 'b']`

## See also

- the `reduce` method
  that performs a similar operation
- the `filter` method
  that allows you to filter the elements of an array
- the `map` and `forEach` methods
  that allow you to apply a function to each element of an array
- the `some` and `every` methods
  that perform an array check

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