Map and Set basics

Map.js

let members = new Map([["Sam", 56], ["Sandy", 86]]);

let youngestMemberAge = Math.min(...members.values()) // 86

let Over60s = new Map(
  [...members].filter(([name, age]) => 60 < age)
);

let Over60sUserNames = new Map(
  [...members].map(([name, age]) => {
    return [`${name}_${age}`, name];
  })
);


let newMembers = new Map([["John", 38], ["Paul", 42]]);
let allMembers = [...members, ...newMembers];

allMembers.forEach(member => members.set(member.name, member.age));