Practice: Working with Map Objects

Instance methods

Map.prototype.clear(): Removes all key-value pairs from the Map object.
Map.prototype.delete(): Returns true if an element in the Map object existed and has been removed, or false if the element does not exist. map.has(key) will return false afterwards.
Map.prototype.entries(): Returns a new Iterator object that contains a two-member array of [key, value] for each element in the Map object in insertion order.
Map.prototype.forEach(): Calls callbackFn once for each key-value pair present in the Map object, in insertion order. If a thisArg parameter is provided to forEach, it will be used as the this value for each callback.
Map.prototype.get(): Returns the value associated to the passed key, or undefined if there is none.
Map.prototype.has(): Returns a boolean indicating whether a value has been associated with the passed key in the Map object or not.
Map.prototype.keys(): Returns a new Iterator object that contains the keys for each element in the Map object in insertion order.
Map.prototype.set(): Sets the value for the passed key in the Map object. Returns the Map object.
Map.prototype.values(): Returns a new Iterator object that contains the values for each element in the Map object in insertion order.
Map.prototype[@@iterator](): Returns a new Iterator object that contains a two-member array of [key, value] for each element in the Map object in insertion order.