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Lodash _.reduceRight


The lodash _.reduceRight() method iterates over an array from right to left, performing a reducer function on each element and returning a single accumulated value.


_.reduceRight(array, reducerFunction, initialValue)


  • array: The array to iterate over.
  • reducerFunction: The function to execute on each element in the array.
  • initialValue (optional): The initial value of the accumulator.

Return: The accumulated value.


const numbers = [1, 2, 3, 4, 5];
const sum = _.reduceRight(numbers, (accumulator, currentValue) => accumulator + currentValue);
console.log(sum); // Output: 15

In this example, the reduceRight method starts with the last element in the numbers array (5) and iterates through the array from right to left. The reducer function adds each element to the accumulator, resulting in a final value of 15.

If an initial value is not provided, the reduceRight method will use the last element of the array as the initial value and skip the last iteration.


const numbers = [1, 2, 3, 4, 5];
const sum = _.reduceRight(numbers, (accumulator, currentValue) => accumulator + currentValue, 0);
console.log(sum); // Output: 15

In this example, the reduceRight method starts with an initial value of 0 and iterates through the array from right to left, resulting in a final value of 15.

Note that the reduceRight method can also be used with objects instead of arrays, iterating over the object in reverse order of the keys.