What does console.log(['a', 'b', 'c'].reduceRight((acc, x) => acc + x)) print? JavaScript Arrays and Iteration

Answer, C. cba

A. abc

Assumes reduceRight processes the array in the same left to right order as reduce. reduceRight always folds the array starting from the last element and moving toward the first.

B. cab

Assumes the last element ends up somewhere in the middle of the result rather than at the very front. reduceRight starts its very first step with the last two elements, so the last element always leads the accumulation.

C. cba

Correct. reduceRight folds the array from right to left, so starting from "c" and appending "b" then "a" produces the string "cba".

D. undefined

Assumes reduceRight without an explicit initial value fails the same way reduce does on an empty array. The array here is not empty, so the last element simply becomes the seed and the reduction proceeds normally.

reduceRight behaves exactly like reduce except that it processes the array from the last element toward the first. Without an initial value it seeds the accumulator with the last element rather than the first, then works backward through the rest of the array.