29 lines
1 KiB
JavaScript
29 lines
1 KiB
JavaScript
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'use strict';
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var $ = require('../internals/export');
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var IS_PURE = require('../internals/is-pure');
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var anObject = require('../internals/an-object');
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var aFunction = require('../internals/a-function');
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var getMapIterator = require('../internals/get-map-iterator');
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var iterate = require('../internals/iterate');
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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: IS_PURE }, {
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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 accumulator, step;
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aFunction(callbackfn);
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if (arguments.length > 1) accumulator = arguments[1];
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else {
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step = iterator.next();
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if (step.done) throw TypeError('Reduce of empty map with no initial value');
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accumulator = step.value[1];
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}
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iterate(iterator, function (key, value) {
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accumulator = callbackfn(accumulator, value, key, map);
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}, undefined, true, true);
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return accumulator;
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}
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});
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