2 // https://github.com/tc39/proposal-iterator-helpers
3 var $ = require('../internals/export');
4 var apply = require('../internals/function-apply');
5 var aCallable = require('../internals/a-callable');
6 var anObject = require('../internals/an-object');
7 var createAsyncIteratorProxy = require('../internals/async-iterator-create-proxy');
9 var AsyncIteratorProxy = createAsyncIteratorProxy(function (Promise, args) {
11 var filterer = state.filterer;
13 return new Promise(function (resolve, reject) {
14 var loop = function () {
16 Promise.resolve(anObject(apply(state.next, state.iterator, args))).then(function (step) {
18 if (anObject(step).done) {
20 resolve({ done: true, value: undefined });
22 var value = step.value;
23 Promise.resolve(filterer(value)).then(function (selected) {
24 selected ? resolve({ done: false, value: value }) : loop();
27 } catch (err) { reject(err); }
29 } catch (error) { reject(error); }
36 $({ target: 'AsyncIterator', proto: true, real: true }, {
37 filter: function filter(filterer) {
38 return new AsyncIteratorProxy({
39 iterator: anObject(this),
40 filterer: aCallable(filterer)