JavaScript Array reduceRight()
Examples
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 »
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 »
Description
The reduceRight() method executes a reducer function for each array element.
The reduceRight() method works from right to left.
The reduceRight() method returns a single value: the function's accumulated result.
The reduceRight() method does not execute the function for empty elements.
Note
At the first callback, there is no return value from the previous callback.
Normally, the last array element is used as initial value, and the iteration starts from the element before.
If an initial value is supplied, this is used, and the iteration starts from last element.
See Also:
Syntax
array.reduceRight(function(total, currentValue, currentIndex, arr), initialValue)
Parameters
| Parameter | Description | ||||||||
| function() | Required. A function to be run for each element in the array. |
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Reducer function parameters:
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| initialValue | Optional. A value to be passed to the function as the initial value |
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Return Value
| The accumulated result from the last call of the callback function. |
Array Tutorials:
Browser Support
reduceRight() is an ECMAScript5 (ES5) feature.
ES5 (JavaScript 2009) is fully supported in all modern browsers since July 2013:
| Chrome 23 |
IE/Edge 11 |
Firefox 21 |
Safari 6 |
Opera 15 |
| Sep 2012 | Sep 2012 | Apr 2013 | Jul 2012 | Jul 2013 |
