How to implement dynamic addition to an array?

Question

JavaScript

How can this code be simplified?

const savedUser_serverId = saved_user[0].server_id;
    servers.push(savedUser_serverId);
    switch (savedUser_serverId) {
      case 1:
        servers.push(2);
        servers.push(3);
        break;
      case 2:
        servers.push(1);
        servers.push(3);
        break;
      case 3:
        servers.push(1);
        servers.push(2);
        break;
    }

Answer 1

servers.push(savedUser_serverId, ...(({
  1: [ 2, 3 ],
  2: [ 1, 3 ],
  3: [ 1, 2 ],
})[savedUser_serverId] ?? []))

Answer 2

If there is no difference in what order the values ​​are pushed, then

servers.push(savedUser_serverId);
servers.push((savedUser_serverId + 1) % 4 + 1);
servers.push((savedUser_serverId + 2) % 4 + 1);