text: const app = require("./app");
  const debug = require("debug")("elearning");
  const http = require("http");
  
  const normalizePort = val => {
      var port = parseInt(val, 10);
  
      if (isNaN(port)) {
          // named pipe
          return val;
      }
  
      if (port >= 0) {
          // port number
          return port;
      }
  
      return false;
  };
  
  const onError = error => {
      if (error.syscall !== "listen") {
          throw error;
      }
      const bind = typeof port === "string" ? "pipe " + port : "port " + port;
      switch (error.code) {
          case "EACCES":
              console.error(bind + " requires elevated privileges");
              process.exit(1);
              break;
          case "EADDRINUSE":
              console.error(bind + " is already in use");
              process.exit(1);
              break;
          default:
              throw error;
      }
  };
  
  const onListening = () => {
      const addr = server.address();
      const bind = typeof port === "string" ? "pipe " + port : "port " + port;
      debug("Listening on " + bind);
  };
  
  const port = normalizePort(process.env.PORT || "3001");
  app.set("port", port);
  
  const server = http.createServer(app);
  server.on("error", onError);
  server.on("listening", onListening);
  server.listen(port);
  