41 lines
1.2 KiB
JavaScript
41 lines
1.2 KiB
JavaScript
var baseAssignValue = require('./_baseAssignValue'),
|
|
createAggregator = require('./_createAggregator');
|
|
|
|
/** Used for built-in 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` 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).
|
|
*
|
|
* @static
|
|
* @memberOf _
|
|
* @since 0.5.0
|
|
* @category Collection
|
|
* @param {Array|Object} collection The collection to iterate over.
|
|
* @param {Function} [iteratee=_.identity] The iteratee to transform keys.
|
|
* @returns {Object} Returns the composed aggregate object.
|
|
* @example
|
|
*
|
|
* _.countBy([6.1, 4.2, 6.3], Math.floor);
|
|
* // => { '4': 1, '6': 2 }
|
|
*
|
|
* // The `_.property` iteratee shorthand.
|
|
* _.countBy(['one', 'two', 'three'], 'length');
|
|
* // => { '3': 2, '5': 1 }
|
|
*/
|
|
var countBy = createAggregator(function(result, value, key) {
|
|
if (hasOwnProperty.call(result, key)) {
|
|
++result[key];
|
|
} else {
|
|
baseAssignValue(result, key, 1);
|
|
}
|
|
});
|
|
|
|
module.exports = countBy;
|