map stored how in javascript const code example

Example 1: initialize a map js

let map = new Map()
map['bla'] = 'blaa'
map['bla2'] = 'blaaa2'

console.log(map)  // Map { bla: 'blaa', bla2: 'blaaa2' }

Example 2: is maps used in js

console.log(typeof(userRoles)); // object
console.log(userRoles instanceof Map); // true