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Editing: esnext.iterator.reduce.js
'use strict'; // https://github.com/tc39/proposal-iterator-helpers var $ = require('../internals/export'); var iterate = require('../internals/iterate'); var aCallable = require('../internals/a-callable'); var getIteratorDirect = require('../internals/get-iterator-direct'); var $TypeError = TypeError; $({ target: 'Iterator', proto: true, real: true, forced: true }, { reduce: function reduce(reducer /* , initialValue */) { var record = getIteratorDirect(this); aCallable(reducer); var noInitial = arguments.length < 2; var accumulator = noInitial ? undefined : arguments[1]; var counter = 0; iterate(record, function (value) { if (noInitial) { noInitial = false; accumulator = value; } else { accumulator = reducer(accumulator, value, counter); } counter++; }, { IS_RECORD: true }); if (noInitial) throw $TypeError('Reduce of empty iterator with no initial value'); return accumulator; } });
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