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'use strict'; var $ = require('../internals/export'); var aMap = require('../internals/a-map'); var MapHelpers = require('../internals/map-helpers');
var get = MapHelpers.get; var has = MapHelpers.has; var set = MapHelpers.set;
// `Map.prototype.emplace` method
// https://github.com/tc39/proposal-upsert
$({ target: 'Map', proto: true, real: true, forced: true }, { emplace: function emplace(key, handler) { var map = aMap(this); var value, inserted; if (has(map, key)) { value = get(map, key); if ('update' in handler) { value = handler.update(value, key, map); set(map, key, value); } return value; } inserted = handler.insert(key, map); set(map, key, inserted); return inserted; } });
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