2 // https://github.com/tc39/proposal-iterator-helpers
3 var $ = require('../internals/export');
4 var aFunction = require('../internals/a-function');
5 var anObject = require('../internals/an-object');
6 var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
8 var AsyncIteratorProxy = createAsyncIteratorProxy(function (arg, Promise) {
10 var mapper = state.mapper;
12 return Promise.resolve(anObject(state.next.call(state.iterator, arg))).then(function (step) {
13 if (anObject(step).done) {
15 return { done: true, value: undefined };
17 return Promise.resolve(mapper(step.value)).then(function (value) {
18 return { done: false, value: value };
23 $({ target: 'AsyncIterator', proto: true, real: true }, {
24 map: function map(mapper) {
25 return new AsyncIteratorProxy({
26 iterator: anObject(this),
27 mapper: aFunction(mapper)