Iniciando aplicação com Node.js, Express e Babel 7

Server.js

import Express from 'express';

export class Server {
  app = Express();

  startup() {
    this.setupRoutes();

    this.app.listen(3000, () => console.log("Listening..."));
  }

  setupRoutes() {
    this.app.get("/teste", (req, res) => {
      res.send("Funcionando :)");
    });
  }
}