Permalink
Cannot retrieve contributors at this time
| import baseAssignValue from './.internal/baseAssignValue.js' | |
| import reduce from './reduce.js' | |
| /** Used to check objects for own properties. */ | |
| const hasOwnProperty = Object.prototype.hasOwnProperty | |
| /** | |
| * Creates an object composed of keys generated from the results of running | |
| * each element of `collection` thru `iteratee`. The corresponding value of | |
| * each key is the number of times the key was returned by `iteratee`. The | |
| * iteratee is invoked with one argument: (value). | |
| * | |
| * @since 0.5.0 | |
| * @category Collection | |
| * @param {Array|Object} collection The collection to iterate over. | |
| * @param {Function} iteratee The iteratee to transform keys. | |
| * @returns {Object} Returns the composed aggregate object. | |
| * @example | |
| * | |
| * const users = [ | |
| * { 'user': 'barney', 'active': true }, | |
| * { 'user': 'betty', 'active': true }, | |
| * { 'user': 'fred', 'active': false } | |
| * ] | |
| * | |
| * countBy(users, value => value.active); | |
| * // => { 'true': 2, 'false': 1 } | |
| */ | |
| function countBy(collection, iteratee) { | |
| return reduce(collection, (result, value, key) => { | |
| key = iteratee(value) | |
| if (hasOwnProperty.call(result, key)) { | |
| ++result[key] | |
| } else { | |
| baseAssignValue(result, key, 1) | |
| } | |
| return result | |
| }, {}) | |
| } | |
| export default countBy |