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4 years ago
'use strict';
var $ = require('../internals/export');
var iterate = require('../internals/iterate');
var aFunction = require('../internals/a-function');
// `Map.keyBy` method
// https://github.com/tc39/proposal-collection-methods
$({ target: 'Map', stat: true }, {
keyBy: function keyBy(iterable, keyDerivative) {
var newMap = new this();
aFunction(keyDerivative);
var setter = aFunction(newMap.set);
iterate(iterable, function (element) {
setter.call(newMap, keyDerivative(element), element);
});
return newMap;
}
});