ES6 Maps

Maps represent key-value pairs, similar to objects.

You may be wondering why we need a map data structure if objects can also be used as maps. The answer is simple: maps can have keys of any type, and the keys are not converted to strings. Therefore, 0 and '0' are two different, and valid keys.

Objects are also valid keys for maps. They are not converted to '[object Object]'. Note though, that objects are reference types. Therefore, using the {} object literal twice as keys will result in two different entries in the map.

We can build maps in multiple ways. We can either use the set method to add values to the map or pass an array of key-value pairs to the map constructor.