| 1 | ;
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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.keyBy` 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 | keyBy: function keyBy(iterable, keyDerivative) {
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| 10 | var newMap = new this();
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| 11 | aFunction(keyDerivative);
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| 12 | var setter = aFunction(newMap.set);
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| 13 | iterate(iterable, function (element) {
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| 14 | setter.call(newMap, keyDerivative(element), element);
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| 15 | });
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| 16 | return newMap;
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| 17 | }
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| 18 | });
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