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29 lines
928 B
29 lines
928 B
4 weeks ago
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'use strict';
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var $ = require('../internals/export');
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var aCallable = require('../internals/a-callable');
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var aMap = require('../internals/a-map');
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var iterate = require('../internals/map-iterate');
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var $TypeError = TypeError;
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// `Map.prototype.reduce` method
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// https://github.com/tc39/proposal-collection-methods
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$({ target: 'Map', proto: true, real: true, forced: true }, {
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reduce: function reduce(callbackfn /* , initialValue */) {
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var map = aMap(this);
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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(map, function (value, key) {
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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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});
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if (noInitial) throw new $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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