| var createAggregator = require('../internal/createAggregator'); |
| |
| /** Used for native method references. */ |
| var objectProto = Object.prototype; |
| |
| /** Used to check objects for own properties. */ |
| var hasOwnProperty = objectProto.hasOwnProperty; |
| |
| /** |
| * Creates an object composed of keys generated from the results of running |
| * each element of `collection` through `iteratee`. The corresponding value |
| * of each key is an array of the elements responsible for generating the key. |
| * The `iteratee` is bound to `thisArg` and invoked with three arguments: |
| * (value, index|key, collection). |
| * |
| * If a property name is provided for `iteratee` the created `_.property` |
| * style callback returns the property value of the given element. |
| * |
| * If a value is also provided for `thisArg` the created `_.matchesProperty` |
| * style callback returns `true` for elements that have a matching property |
| * value, else `false`. |
| * |
| * If an object is provided for `iteratee` the created `_.matches` style |
| * callback returns `true` for elements that have the properties of the given |
| * object, else `false`. |
| * |
| * @static |
| * @memberOf _ |
| * @category Collection |
| * @param {Array|Object|string} collection The collection to iterate over. |
| * @param {Function|Object|string} [iteratee=_.identity] The function invoked |
| * per iteration. |
| * @param {*} [thisArg] The `this` binding of `iteratee`. |
| * @returns {Object} Returns the composed aggregate object. |
| * @example |
| * |
| * _.groupBy([4.2, 6.1, 6.4], function(n) { |
| * return Math.floor(n); |
| * }); |
| * // => { '4': [4.2], '6': [6.1, 6.4] } |
| * |
| * _.groupBy([4.2, 6.1, 6.4], function(n) { |
| * return this.floor(n); |
| * }, Math); |
| * // => { '4': [4.2], '6': [6.1, 6.4] } |
| * |
| * // using the `_.property` callback shorthand |
| * _.groupBy(['one', 'two', 'three'], 'length'); |
| * // => { '3': ['one', 'two'], '5': ['three'] } |
| */ |
| var groupBy = createAggregator(function(result, value, key) { |
| if (hasOwnProperty.call(result, key)) { |
| result[key].push(value); |
| } else { |
| result[key] = [value]; |
| } |
| }); |
| |
| module.exports = groupBy; |