first

node_modules/core-js/modules/esnext.map.group-by.js

@@ -0,0 +1,31 @@
+'use strict';
+var $ = require('../internals/export');
+var uncurryThis = require('../internals/function-uncurry-this');
+var aCallable = require('../internals/a-callable');
+var requireObjectCoercible = require('../internals/require-object-coercible');
+var iterate = require('../internals/iterate');
+var MapHelpers = require('../internals/map-helpers');
+var IS_PURE = require('../internals/is-pure');
+
+var Map = MapHelpers.Map;
+var has = MapHelpers.has;
+var get = MapHelpers.get;
+var set = MapHelpers.set;
+var push = uncurryThis([].push);
+
+// `Map.groupBy` method
+// https://github.com/tc39/proposal-array-grouping
+$({ target: 'Map', stat: true, forced: IS_PURE }, {
+  groupBy: function groupBy(items, callbackfn) {
+    requireObjectCoercible(items);
+    aCallable(callbackfn);
+    var map = new Map();
+    var k = 0;
+    iterate(items, function (value) {
+      var key = callbackfn(value, k++);
+      if (!has(map, key)) set(map, key, [value]);
+      else push(get(map, key), value);
+    });
+    return map;
+  }
+});