How to catch the exception "Port is already used"

[huuson235]

I want my app to quit whenever raising exception port is already used. How can I handle it?

[darrachequesne]

You can catch the 'EADDRINUSE' error event:

const httpServer = require("http").createServer();
const io = require("socket.io")(httpServer, { /* ... */ });
const port = 8080;

io.on("connection", (socket) => { /* ... */ });

server.listen(port, () => {
  console.log(`server listening on port ${port}`)
});

server.on("error", (e) => {
  if (e.code === "EADDRINUSE") {
    process.exit(1);
  }
});

Reference: https://nodejs.org/api/net.html#net_server_listen