esnext.map.update.js

'use strict';
var $ = require('../internals/export');
var aCallable = require('../internals/a-callable');
var aMap = require('../internals/a-map');
var MapHelpers = require('../internals/map-helpers');

var $TypeError = TypeError;
var get = MapHelpers.get;
var has = MapHelpers.has;
var set = MapHelpers.set;

// `Map.prototype.update` method
// https://github.com/tc39/proposal-collection-methods
$({ target: 'Map', proto: true, real: true, forced: true }, {
  update: function update(key, callback /* , thunk */) {
    var map = aMap(this);
    var length = arguments.length;
    aCallable(callback);
    var isPresentInMap = has(map, key);
    if (!isPresentInMap && length < 3) {
      throw new $TypeError('Updating absent value');
    }
    var value = isPresentInMap ? get(map, key) : aCallable(length > 2 ? arguments[2] : undefined)(key, map);
    set(map, key, callback(value, key, map));
    return map;
  }
});