{
    1: { id: 1, name: "John" }
    2: { id: 2, name: "Jim" }
    3: { id: 3, name: "James" }
}

delUser(id) {
    const users = this.state.users;
    delete users[id];
    this.setState(users);
}

addChangeUser(id, name) {
    const users = this.state.users;
    users[id] = {id: id, name: name};
    this.setState(users);
}

addChangeUser(4, 'Jane);
addChangeUser(2, 'Peter');
delUser(2);

let user = new Map();
user.set(4, { id: 4, name: "Jane" }); //adds with id (4) as key
user.myMap.set(2, { id: 2, name: "Peter" }); // set user #2 to "Peter"
user.delete(3); //deletes user with id 3

function add( user ) {
  this.setState( users => {
    users[ user.id ] = user
    return users
  }
}

function remove( id ) {
  this.setState( users => {
    delete users[ id ]
    return users
}

this.setState({
  ...this.state,
  4: { id: 4, name: "Jane" },
}

let prevState = this.state;
let {"2": id, ...nextState} = prevState;
this.setState({
  ...nextState,
}

this.setState({
  ...this.state,
  2: {
    ...this.state["2"],
    name: "Peter",
  }
}