--- /dev/null
+'use strict';
+var $ = require('../internals/export');
+var IS_PURE = require('../internals/is-pure');
+var anObject = require('../internals/an-object');
+var aFunction = require('../internals/a-function');
+
+// `Set.prototype.update` method
+// https://github.com/tc39/proposal-collection-methods
+$({ target: 'Map', proto: true, real: true, forced: IS_PURE }, {
+ update: function update(key, callback /* , thunk */) {
+ var map = anObject(this);
+ var length = arguments.length;
+ aFunction(callback);
+ var isPresentInMap = map.has(key);
+ if (!isPresentInMap && length < 3) {
+ throw TypeError('Updating absent value');
+ }
+ var value = isPresentInMap ? map.get(key) : aFunction(length > 2 ? arguments[2] : undefined)(key, map);
+ map.set(key, callback(value, key, map));
+ return map;
+ }
+});