mout/array/reduceRight.js

    /**
     * Array reduceRight
     */
    function reduceRight(arr, fn, initVal) {
        // check for args.length since initVal might be "undefined" see #gh-57
        var hasInit = arguments.length > 2;

        if (arr == null || !arr.length) {
            if (hasInit) {
                return initVal;
            } else {
                throw new Error('reduce of empty array with no initial value');
            }
        }

        var i = arr.length, result = initVal, value;
        while (--i >= 0) {
            // we iterate over sparse items since there is no way to make it
            // work properly on IE 7-8. see #64
            value = arr[i];
            if (!hasInit) {
                result = value;
                hasInit = true;
            } else {
                result = fn(result, value, i, arr);
            }
        }
        return result;
    }

    module.exports = reduceRight;