reduceRight.js

import reduce from './reduce';

var slice = Array.prototype.slice;

/**
 * Same as [`reduce`]{@link module:Collections.reduce}, only operates on `array` in reverse order.
 *
 * @name reduceRight
 * @static
 * @memberOf module:Collections
 * @method
 * @see [async.reduce]{@link module:Collections.reduce}
 * @alias foldr
 * @category Collection
 * @param {Array} array - A collection to iterate over.
 * @param {*} memo - The initial state of the reduction.
 * @param {Function} iteratee - A function applied to each item in the
 * array to produce the next step in the reduction. The `iteratee` is passed a
 * `callback(err, reduction)` which accepts an optional error as its first
 * argument, and the state of the reduction as the second. If an error is
 * passed to the callback, the reduction is stopped and the main `callback` is
 * immediately called with the error. Invoked with (memo, item, callback).
 * @param {Function} [callback] - A callback which is called after all the
 * `iteratee` functions have finished. Result is the reduced value. Invoked with
 * (err, result).
 */
export default function reduceRight (array, memo, iteratee, callback) {
    var reversed = slice.call(array).reverse();
    reduce(reversed, memo, iteratee, callback);
}