29 lines
1 KiB
JavaScript
Executable file
29 lines
1 KiB
JavaScript
Executable file
'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 }, {
|
|
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;
|
|
}
|
|
});
|