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31 lines
1.1 KiB
31 lines
1.1 KiB
'use strict'; |
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var $ = require('../internals/export'); |
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var global = require('../internals/global'); |
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var anObject = require('../internals/an-object'); |
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var aCallable = require('../internals/a-callable'); |
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var getMapIterator = require('../internals/get-map-iterator'); |
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var iterate = require('../internals/iterate'); |
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var TypeError = global.TypeError; |
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// `Map.prototype.reduce` method |
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// https://github.com/tc39/proposal-collection-methods |
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$({ target: 'Map', proto: true, real: true, forced: true }, { |
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reduce: function reduce(callbackfn /* , initialValue */) { |
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var map = anObject(this); |
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var iterator = getMapIterator(map); |
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var noInitial = arguments.length < 2; |
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var accumulator = noInitial ? undefined : arguments[1]; |
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aCallable(callbackfn); |
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iterate(iterator, function (key, value) { |
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if (noInitial) { |
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noInitial = false; |
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accumulator = value; |
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} else { |
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accumulator = callbackfn(accumulator, value, key, map); |
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} |
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}, { AS_ENTRIES: true, IS_ITERATOR: true }); |
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if (noInitial) throw TypeError('Reduce of empty map with no initial value'); |
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return accumulator; |
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} |
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});
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