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Last change
on this file since 6c1585f was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
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initial commit
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File size:
755 bytes
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| 1 | 'use strict';
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| 2 | var $ = require('../internals/export');
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| 3 | var iterate = require('../internals/iterate');
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| 4 | var aFunction = require('../internals/a-function');
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| 5 |
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| 6 | // `Map.groupBy` method
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| 7 | // https://github.com/tc39/proposal-collection-methods
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| 8 | $({ target: 'Map', stat: true }, {
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| 9 | groupBy: function groupBy(iterable, keyDerivative) {
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| 10 | var newMap = new this();
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| 11 | aFunction(keyDerivative);
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| 12 | var has = aFunction(newMap.has);
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| 13 | var get = aFunction(newMap.get);
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| 14 | var set = aFunction(newMap.set);
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| 15 | iterate(iterable, function (element) {
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| 16 | var derivedKey = keyDerivative(element);
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| 17 | if (!has.call(newMap, derivedKey)) set.call(newMap, derivedKey, [element]);
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| 18 | else get.call(newMap, derivedKey).push(element);
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| 19 | });
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| 20 | return newMap;
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| 21 | }
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| 22 | });
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