Map

map.js

class Person {
  constructor (name, score) {
    this.name = name
    this.score = score
  }
}

const alice_foo = new Person('Alice', 10)
const alice_bar = new Person('Alice', 50)

const people_object = {}
people_object[alice_foo.name] = alice_foo.score
people_object[alice_bar.name] = alice_bar.score
console.log(people_object[alice_foo.name] === alice_bar.score) // Oops! true

const people_map = new Map()
people_map.set(alice_foo, alice_foo.score)
people_map.set(alice_bar, alice_bar.score)
console.log(people_map.get(alice_foo) === alice_foo.score) // Correct! true