--- /dev/null
+var global = require('../internals/global');
+var bind = require('../internals/function-bind-context');
+var uncurryThis = require('../internals/function-uncurry-this');
+var IndexedObject = require('../internals/indexed-object');
+var toObject = require('../internals/to-object');
+var toPropertyKey = require('../internals/to-property-key');
+var lengthOfArrayLike = require('../internals/length-of-array-like');
+var objectCreate = require('../internals/object-create');
+var arrayFromConstructorAndList = require('../internals/array-from-constructor-and-list');
+
+var Array = global.Array;
+var push = uncurryThis([].push);
+
+module.exports = function ($this, callbackfn, that, specificConstructor) {
+ var O = toObject($this);
+ var self = IndexedObject(O);
+ var boundFunction = bind(callbackfn, that);
+ var target = objectCreate(null);
+ var length = lengthOfArrayLike(self);
+ var index = 0;
+ var Constructor, key, value;
+ for (;length > index; index++) {
+ value = self[index];
+ key = toPropertyKey(boundFunction(value, index, O));
+ // in some IE10 builds, `hasOwnProperty` returns incorrect result on integer keys
+ // but since it's a `null` prototype object, we can safely use `in`
+ if (key in target) push(target[key], value);
+ else target[key] = [value];
+ }
+ if (specificConstructor) {
+ Constructor = specificConstructor(O);
+ if (Constructor !== Array) {
+ for (key in target) target[key] = arrayFromConstructorAndList(Constructor, target[key]);
+ }
+ } return target;
+};