'use strict';
|
var $ = require('../internals/export');
|
var aCallable = require('../internals/a-callable');
|
var getIterator = require('../internals/get-iterator');
|
var iterate = require('../internals/iterate');
|
|
// `Map.groupBy` method
|
// https://github.com/tc39/proposal-collection-methods
|
$({ target: 'Map', stat: true }, {
|
groupBy: function groupBy(iterable, keyDerivative) {
|
aCallable(keyDerivative);
|
var iterator = getIterator(iterable);
|
var newMap = new this();
|
var has = aCallable(newMap.has);
|
var get = aCallable(newMap.get);
|
var set = aCallable(newMap.set);
|
iterate(iterator, function (element) {
|
var derivedKey = keyDerivative(element);
|
if (!has.call(newMap, derivedKey)) set.call(newMap, derivedKey, [element]);
|
else get.call(newMap, derivedKey).push(element);
|
}, { IS_ITERATOR: true });
|
return newMap;
|
}
|
});
|
