setbeginnerconst m = new Map()
m.set('a', 1)
m.set('b', 2)
console.log(m.size) // β 2Use Map.set() to add or update a key-value pair; it returns the map itself.
After calling set(key, value), get(key) returns that value.
Challenge: Verify that get('a') returns 1 after set('a', 1).