What's the difference between ES6 Map and WeakMap?

Question

Looking this and this MDN pages it seems like the only difference between Maps and WeakMaps is a missing \"size\" property for WeakMaps. But is this true? What\'s the differ

Answer 1

Another difference (source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap):

Keys of WeakMaps are of the type Object only. Primitive data types as keys are not allowed (e.g. a Symbol can't be a WeakMap key).

Nor can a string, number, or boolean be used as a WeakMap key. A Map can use primitive values for keys.

w = new WeakMap;
w.set('a', 'b'); // Uncaught TypeError: Invalid value used as weak map key

m = new Map
m.set('a', 'b'); // Works