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JavaScript Array reduceRight()

Example 1

Subtract the numbers in the array, starting from the end:

const numbers = [175, 50, 25];

document.getElementById("demo").innerHTML = numbers.reduceRight(myFunc);

function myFunc(total, num) {
  return total - num;
}
Try it Yourself »

Definition and Usage

reduceRight() executes a reducer function for each element of an array.

reduceRight() works from right to left.

reduceRight() returns a single value which is the function's accumulated result.

reduceRight() does not execute the function for empty elements.

See Also:

Array.reduce()

Example 2

Subtract the numbers, right-to-left, and display the sum:

const numbers = [2, 45, 30, 100];
document.getElementById("demo").innerHTML = numbers.reduceRight(getSum);

function getSum(total, num) {
  return total - num;
}
Try it Yourself »

Browser Support

reduceRight() is an ES5 feature (JavaScript 2009). It is fully supported in all modern browsers:

Chrome IE Edge Firefox Safari Opera
Yes 9.0 Yes Yes Yes Yes


Syntax

array.reduceRight(function(total, currentValue, currentIndex, arr), initialValue)

Parameters

function() Required.
A function to be run for each element in the array.
total Required.
The initialValue, or the previously returned value of the function.
currentValue Required.
The value of the current element.
currentIndex Optional.
The index of the current element.
arr Optional.
The array the element belongs to.
initialValue Optional. A value to be passed to the function as the initial value

Return Value

The accumulated result from the last call of the callback function.