feat(Symbol.iterator): no longer polyfilled

src/internal/symbol/iterator.ts

@@ -1,38 +1,16 @@
-import { root } from '../util/root';
 
-export function symbolIteratorPonyfill(root: any) {
- const Symbol: any = root.Symbol;
-
- if (typeof Symbol === 'function') {
- if (!Symbol.iterator) {
- Symbol.iterator = Symbol('iterator polyfill');
- }
- return Symbol.iterator;
- } else {
- // [for Mozilla Gecko 27-35:](https://mzl.la/2ewE1zC)
- const { Set } = root;
- if (Set && typeof new Set()['@@iterator'] === 'function') {
- return '@@iterator';
- }
- const { Map } = root;
- // required for compatability with es6-shim
- if (Map) {
- let keys = Object.getOwnPropertyNames(Map.prototype);
- for (let i = 0; i < keys.length; ++i) {
- let key = keys[i];
- // according to spec, Map.prototype[@@iterator] and Map.orototype.entries must be equal.
- if (key !== 'entries' && key !== 'size' && Map.prototype[key] === Map.prototype['entries']) {
- return key;
- }
- }
- }
- return '@@iterator';
- }
+/* NOTE: Warning users that they don't have a Symbol.iterator
+ polyfill. We don't want to throw on this, because it's not required
+ by the library. However it will provide clues to users on older
+ browsers why things like `from(iterable)` doesn't work. */
+if (!Symbol || !Symbol.iterator) {
+ console.warn('RxJS: Symbol.observable does not exist');
 }
 
-export const iterator = symbolIteratorPonyfill(root);
+/** The native Symbol.iterator instance or a string */
+export const iterator = Symbol && Symbol.iterator || '@@iterator';
 
 /**
- * @deprecated use iterator instead
+ * @deprecated use {@link iterator} instead
  */
 export const $$iterator = iterator;