8 /* eslint-disable no-unused-vars */
9 var getOwnPropertySymbols = Object.getOwnPropertySymbols;
10 var hasOwnProperty = Object.prototype.hasOwnProperty;
11 var propIsEnumerable = Object.prototype.propertyIsEnumerable;
13 function toObject(val) {
14 if (val === null || val === undefined) {
15 throw new TypeError('Object.assign cannot be called with null or undefined');
21 function shouldUseNative() {
27 // Detect buggy property enumeration order in older V8 versions.
29 // https://bugs.chromium.org/p/v8/issues/detail?id=4118
30 var test1 = new String('abc'); // eslint-disable-line no-new-wrappers
32 if (Object.getOwnPropertyNames(test1)[0] === '5') {
36 // https://bugs.chromium.org/p/v8/issues/detail?id=3056
38 for (var i = 0; i < 10; i++) {
39 test2['_' + String.fromCharCode(i)] = i;
41 var order2 = Object.getOwnPropertyNames(test2).map(function (n) {
44 if (order2.join('') !== '0123456789') {
48 // https://bugs.chromium.org/p/v8/issues/detail?id=3056
50 'abcdefghijklmnopqrst'.split('').forEach(function (letter) {
51 test3[letter] = letter;
53 if (Object.keys(Object.assign({}, test3)).join('') !==
54 'abcdefghijklmnopqrst') {
60 // We don't expect any of the above to throw, but better to be safe.
65 module.exports = shouldUseNative() ? Object.assign : function (target, source) {
67 var to = toObject(target);
70 for (var s = 1; s < arguments.length; s++) {
71 from = Object(arguments[s]);
73 for (var key in from) {
74 if (hasOwnProperty.call(from, key)) {
79 if (getOwnPropertySymbols) {
80 symbols = getOwnPropertySymbols(from);
81 for (var i = 0; i < symbols.length; i++) {
82 if (propIsEnumerable.call(from, symbols[i])) {
83 to[symbols[i]] = from[symbols[i]];