2 var DESCRIPTORS = require('../internals/descriptors');
3 var fails = require('../internals/fails');
4 var objectKeys = require('../internals/object-keys');
5 var getOwnPropertySymbolsModule = require('../internals/object-get-own-property-symbols');
6 var propertyIsEnumerableModule = require('../internals/object-property-is-enumerable');
7 var toObject = require('../internals/to-object');
8 var IndexedObject = require('../internals/indexed-object');
10 var nativeAssign = Object.assign;
11 var defineProperty = Object.defineProperty;
13 // `Object.assign` method
14 // https://tc39.es/ecma262/#sec-object.assign
15 module.exports = !nativeAssign || fails(function () {
16 // should have correct order of operations (Edge bug)
17 if (DESCRIPTORS && nativeAssign({ b: 1 }, nativeAssign(defineProperty({}, 'a', {
20 defineProperty(this, 'b', {
25 }), { b: 2 })).b !== 1) return true;
26 // should work with symbols and should have deterministic property order (V8 bug)
29 /* global Symbol -- required for testing */
30 var symbol = Symbol();
31 var alphabet = 'abcdefghijklmnopqrst';
33 alphabet.split('').forEach(function (chr) { B[chr] = chr; });
34 return nativeAssign({}, A)[symbol] != 7 || objectKeys(nativeAssign({}, B)).join('') != alphabet;
35 }) ? function assign(target, source) { // eslint-disable-line no-unused-vars -- required for `.length`
36 var T = toObject(target);
37 var argumentsLength = arguments.length;
39 var getOwnPropertySymbols = getOwnPropertySymbolsModule.f;
40 var propertyIsEnumerable = propertyIsEnumerableModule.f;
41 while (argumentsLength > index) {
42 var S = IndexedObject(arguments[index++]);
43 var keys = getOwnPropertySymbols ? objectKeys(S).concat(getOwnPropertySymbols(S)) : objectKeys(S);
44 var length = keys.length;
49 if (!DESCRIPTORS || propertyIsEnumerable.call(S, key)) T[key] = S[key];