Javascript_Map_example.js

const hashmap = new Map()

hashmap.set(1, 'first')
hashmap.set(2, 'second')
hashmap.set(3, 'third')

console.log(' full ... ', hashmap)    // Map(3) { 1 => 'first', 2 => 'second', 3 => 'third' }
console.log('size ... ', hashmap.size)   // returns 3
console.log('.get ... ', hashmap.get(2)) // returns second
console.log('.has ... ', hashmap.has(3)) // returns true
console.log('.has ... ', hashmap.has(4)) // returns false