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 createIteratorProxy = require('../internals/iterator-create-proxy');
7 var callWithSafeIterationClosing = require('../internals/call-with-safe-iteration-closing');
9 var IteratorProxy = createIteratorProxy(function (arg) {
10 var iterator = this.iterator;
11 var result = anObject(this.next.call(iterator, arg));
12 var done = this.done = !!result.done;
13 if (!done) return callWithSafeIterationClosing(iterator, this.mapper, result.value);
16 $({ target: 'Iterator', proto: true, real: true }, {
17 map: function map(mapper) {
18 return new IteratorProxy({
19 iterator: anObject(this),
20 mapper: aFunction(mapper)