12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152 |
- var arrayReduce = require('./_arrayReduce'),
- baseEach = require('./_baseEach'),
- baseIteratee = require('./_baseIteratee'),
- baseReduce = require('./_baseReduce'),
- isArray = require('./isArray');
- /**
- * Reduces `collection` to a value which is the accumulated result of running
- * each element in `collection` thru `iteratee`, where each successive
- * invocation is supplied the return value of the previous. If `accumulator`
- * is not given, the first element of `collection` is used as the initial
- * value. The iteratee is invoked with four arguments:
- * (accumulator, value, index|key, collection).
- *
- * Many lodash methods are guarded to work as iteratees for methods like
- * `_.reduce`, `_.reduceRight`, and `_.transform`.
- *
- * The guarded methods are:
- * `assign`, `defaults`, `defaultsDeep`, `includes`, `merge`, `orderBy`,
- * and `sortBy`
- *
- * @static
- * @memberOf _
- * @since 0.1.0
- * @category Collection
- * @param {Array|Object} collection The collection to iterate over.
- * @param {Function} [iteratee=_.identity] The function invoked per iteration.
- * @param {*} [accumulator] The initial value.
- * @returns {*} Returns the accumulated value.
- * @see _.reduceRight
- * @example
- *
- * _.reduce([1, 2], function(sum, n) {
- * return sum + n;
- * }, 0);
- * // => 3
- *
- * _.reduce({ 'a': 1, 'b': 2, 'c': 1 }, function(result, value, key) {
- * (result[value] || (result[value] = [])).push(key);
- * return result;
- * }, {});
- * // => { '1': ['a', 'c'], '2': ['b'] } (iteration order is not guaranteed)
- */
- function reduce(collection, iteratee, accumulator) {
- var func = isArray(collection) ? arrayReduce : baseReduce,
- initAccum = arguments.length < 3;
- return func(collection, baseIteratee(iteratee, 4), accumulator, initAccum, baseEach);
- }
- module.exports = reduce;
|