_baseReduce.js

/**
 * The base implementation of `_.reduce` and `_.reduceRight`, without support
 * for iteratee shorthands, which iterates over `collection` using `eachFunc`.
 *
 * @private
 * @param {Array|Object} collection The collection to iterate over.
 * @param {Function} iteratee The function invoked per iteration.
 * @param {*} accumulator The initial value.
 * @param {boolean} initAccum Specify using the first or last element of
 *  `collection` as the initial value.
 * @param {Function} eachFunc The function to iterate over `collection`.
 * @returns {*} Returns the accumulated value.
 */
function baseReduce(collection, iteratee, accumulator, initAccum, eachFunc) {
  eachFunc(collection, function(value, index, collection) {
    accumulator = initAccum
      ? (initAccum = false, value)
      : iteratee(accumulator, value, index, collection);
  });
  return accumulator;
}

module.exports = baseReduce;