Javascript Map

Question

Can someone explain me why this code from challenge outputs 1. Code:
let map = new Map([['a', '1'], ['a', '1'], ['a', '2']]);
console.log(map.size);
I know that map keeps only unique value - with different hashcode, but how ['a', '1'] and ['a', '2'] can have same hashcode?

Answer 1

wow, how many challenges 😂💪I will try to win....tomorrow ))

Answer 2

Good question👍I didn't understand too

Answer 3

Map is like a dictionary: one key for one value. There is only a->2 in map. Use Set instead of map to have unique pairs.

Answer 4

Hi Vladi

as @Bartosz says Map should have uniques keys, so what is happening is that each subsequent declaration of "a" overwrites the previous declaration, so your map becomes Map([a,2]) which has length of 1.

If you do a console.log(map.get('a')) you will see output is 2 which is the last declaration.