1 |
3a515b92
|
cagy
|
var baseAssignValue = require('./_baseAssignValue'),
|
2 |
|
|
createAggregator = require('./_createAggregator');
|
3 |
|
|
|
4 |
|
|
/** Used for built-in method references. */
|
5 |
|
|
var objectProto = Object.prototype;
|
6 |
|
|
|
7 |
|
|
/** Used to check objects for own properties. */
|
8 |
|
|
var hasOwnProperty = objectProto.hasOwnProperty;
|
9 |
|
|
|
10 |
|
|
/**
|
11 |
|
|
* Creates an object composed of keys generated from the results of running
|
12 |
|
|
* each element of `collection` thru `iteratee`. The corresponding value of
|
13 |
|
|
* each key is the number of times the key was returned by `iteratee`. The
|
14 |
|
|
* iteratee is invoked with one argument: (value).
|
15 |
|
|
*
|
16 |
|
|
* @static
|
17 |
|
|
* @memberOf _
|
18 |
|
|
* @since 0.5.0
|
19 |
|
|
* @category Collection
|
20 |
|
|
* @param {Array|Object} collection The collection to iterate over.
|
21 |
|
|
* @param {Function} [iteratee=_.identity] The iteratee to transform keys.
|
22 |
|
|
* @returns {Object} Returns the composed aggregate object.
|
23 |
|
|
* @example
|
24 |
|
|
*
|
25 |
|
|
* _.countBy([6.1, 4.2, 6.3], Math.floor);
|
26 |
|
|
* // => { '4': 1, '6': 2 }
|
27 |
|
|
*
|
28 |
|
|
* // The `_.property` iteratee shorthand.
|
29 |
|
|
* _.countBy(['one', 'two', 'three'], 'length');
|
30 |
|
|
* // => { '3': 2, '5': 1 }
|
31 |
|
|
*/
|
32 |
|
|
var countBy = createAggregator(function(result, value, key) {
|
33 |
|
|
if (hasOwnProperty.call(result, key)) {
|
34 |
|
|
++result[key];
|
35 |
|
|
} else {
|
36 |
|
|
baseAssignValue(result, key, 1);
|
37 |
|
|
}
|
38 |
|
|
});
|
39 |
|
|
|
40 |
|
|
module.exports = countBy;
|