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