Singleton Pattern in TS

server.ts

import express, { Application } from "express";

export default class Server {
  private app: Application
  private static instance: Server;

  private constructor() {
    this.app = express();
    this.app.listen(8000, () => {
      console.log("Server started");
    });
  }

  static start() {
    if (Server.instance) {
      console.log('Server already running');
      return this.instance;
    }
    this.instance = new Server();
    console.log("Running on port 8000");
    return this.instance;
  }
}