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Editing: esnext.map.key-by.js
'use strict'; var $ = require('../internals/export'); var call = require('../internals/function-call'); var iterate = require('../internals/iterate'); var aCallable = require('../internals/a-callable'); // `Map.keyBy` method // https://github.com/tc39/proposal-collection-methods $({ target: 'Map', stat: true, forced: true }, { keyBy: function keyBy(iterable, keyDerivative) { var newMap = new this(); aCallable(keyDerivative); var setter = aCallable(newMap.set); iterate(iterable, function (element) { call(setter, newMap, keyDerivative(element), element); }); return newMap; } });
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