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- 'use strict';
- var $ = require('../internals/export');
- var aCallable = require('../internals/a-callable');
- var aSet = require('../internals/a-set');
- var iterate = require('../internals/set-iterate');
- var $TypeError = TypeError;
- // `Set.prototype.reduce` method
- // https://github.com/tc39/proposal-collection-methods
- $({ target: 'Set', proto: true, real: true, forced: true }, {
- reduce: function reduce(callbackfn /* , initialValue */) {
- var set = aSet(this);
- var noInitial = arguments.length < 2;
- var accumulator = noInitial ? undefined : arguments[1];
- aCallable(callbackfn);
- iterate(set, function (value) {
- if (noInitial) {
- noInitial = false;
- accumulator = value;
- } else {
- accumulator = callbackfn(accumulator, value, value, set);
- }
- });
- if (noInitial) throw new $TypeError('Reduce of empty set with no initial value');
- return accumulator;
- }
- });
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