--- /dev/null
+'use strict';
+// https://github.com/tc39/proposal-iterator-helpers
+var $ = require('../internals/export');
+var anObject = require('../internals/an-object');
+var toPositiveInteger = require('../internals/to-positive-integer');
+var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
+
+var AsyncIteratorProxy = createAsyncIteratorProxy(function (arg, Promise) {
+ var iterator = this.iterator;
+ var returnMethod, result;
+ if (!this.remaining--) {
+ result = { done: true, value: undefined };
+ this.done = true;
+ returnMethod = iterator['return'];
+ if (returnMethod !== undefined) {
+ return Promise.resolve(returnMethod.call(iterator)).then(function () {
+ return result;
+ });
+ }
+ return result;
+ } return this.next.call(iterator, arg);
+});
+
+$({ target: 'AsyncIterator', proto: true, real: true }, {
+ take: function take(limit) {
+ return new AsyncIteratorProxy({
+ iterator: anObject(this),
+ remaining: toPositiveInteger(limit)
+ });
+ }
+});