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- 'use strict';
- // https://github.com/tc39/proposal-iterator-helpers
- var $ = require('../internals/export');
- var iterate = require('../internals/iterate');
- var aFunction = require('../internals/a-function');
- var anObject = require('../internals/an-object');
- $({ target: 'Iterator', proto: true, real: true }, {
- reduce: function reduce(reducer /* , initialValue */) {
- anObject(this);
- aFunction(reducer);
- var noInitial = arguments.length < 2;
- var accumulator = noInitial ? undefined : arguments[1];
- iterate(this, function (value) {
- if (noInitial) {
- noInitial = false;
- accumulator = value;
- } else {
- accumulator = reducer(accumulator, value);
- }
- }, { IS_ITERATOR: true });
- if (noInitial) throw TypeError('Reduce of empty iterator with no initial value');
- return accumulator;
- }
- });
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