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 filterer = state.filterer;
12 return new Promise(function (resolve, reject) {
13 var loop = function () {
15 Promise.resolve(anObject(state.next.call(state.iterator, arg))).then(function (step) {
17 if (anObject(step).done) {
19 resolve({ done: true, value: undefined });
21 var value = step.value;
22 Promise.resolve(filterer(value)).then(function (selected) {
23 selected ? resolve({ done: false, value: value }) : loop();
26 } catch (err) { reject(err); }
28 } catch (error) { reject(error); }
35 $({ target: 'AsyncIterator', proto: true, real: true }, {
36 filter: function filter(filterer) {
37 return new AsyncIteratorProxy({
38 iterator: anObject(this),
39 filterer: aFunction(filterer)