API differences

The API for Map and WeakMap is very similar when it comes to standard operations, such as set() and get(). This makes the API very straightforward and contains the following:

• Map.prototype.size: Returns the size of the map; not available on typical objects unless you loop and count
• Map.prototype.set: Sets a value for a given key and returns the entire new map
• Map.prototype.get: Gets a value for a given key and returns undefined if not found
• Map.prototype.delete: Deletes a value for a given key and returns true if deletion was successful, otherwise false
• Map.prototype.has: Checks the map for the presence of an element with the key provided; returns boolean
• Map.prototype.clear: Clears the map; returns nothing
• Map.prototype.forEach: Loops over the map and gives access to each element
• Map.prototype.entries: Returns an iterator on which you can apply the next() method to get the value of the next element in Map, for example, mapIterator.next().value
• Map.prototype.keys: Similar to entries; returns an iterator that can be used to get access to the next value
• Map.prototype.values: Similar to key; returns access to values

The main difference comes in when accessing anything related to keys and the values for a WeakMap. As described earlier, because of the enumeration challenge in case of the WeakMap, methods such as size(), forEach(), entries(), keys(), and values() are not available in  WeakMap.