如何處理 `EADDRINUSE` 錯誤

偵聽時最常見的錯誤之一是 EADDRINUSE。這發生在另一個伺服器已在要求的 port/path/handle 上偵聽時

node:events:489
      throw er; // Unhandled 'error' event
      ^

Error: listen EADDRINUSE: address already in use :::8080
    at Server.setupListenHandle [as _listen2] (node:net:1829:16)
    at listenInCluster (node:net:1877:12)
    at Server.listen (node:net:1965:7)

處理此問題的方法之一是捕捉錯誤並在一段時間後重試

CommonJS
ES 模組
TypeScript

const { createServer } = require("node:http");
const { Server } = require("socket.io");

const httpServer = createServer();
const io = new Server(httpServer);

const PORT = process.env.PORT || 8080;

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

httpServer.on("error", (e) => {
  if (e.code === "EADDRINUSE") {
    console.error("Address already in use, retrying in a few seconds...");
    setTimeout(() => {
      httpServer.listen(PORT);
    }, 1000);
  }
});

httpServer.listen(PORT);

import { createServer } from "node:http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer);

const PORT = process.env.PORT || 8080;

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

httpServer.on("error", (e) => {
  if (e.code === "EADDRINUSE") {
    console.error("Address already in use, retrying in a few seconds...");
    setTimeout(() => {
      httpServer.listen(PORT);
    }, 1000);
  }
});

httpServer.listen(PORT);

import { createServer } from "node:http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer);

const PORT = process.env.PORT || 8080;

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

httpServer.on("error", (e) => {
  if (e.code === "EADDRINUSE") {
    console.error("Address already in use, retrying in a few seconds...");
    setTimeout(() => {
      httpServer.listen(PORT);
    }, 1000);
  }
});

httpServer.listen(PORT);

參考：https://node.dev.org.tw/api/net.html#serverlisten

提示

測試時，您可能不需要使用特定埠。您可以簡單地省略埠，而作業系統會自動為您選擇一個任意未使用的埠

CommonJS
ES 模組
TypeScript

const { createServer } = require("node:http");
const { Server } = require("socket.io");

const httpServer = createServer();
const io = new Server(httpServer);

httpServer.listen(() => {
  const port = httpServer.address().port;
  // ...
});

import { createServer } from "node:http";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer);

httpServer.listen(() => {
  const port = httpServer.address().port;
  // ...
});

import { createServer } from "node:http";
import { type AddressInfo } from "node:net";
import { Server } from "socket.io";

const httpServer = createServer();
const io = new Server(httpServer);

httpServer.listen(() => {
  const port = (httpServer.address() as AddressInfo).port;
  // ...
});

返回範例清單

如何處理 EADDRINUSE 錯誤

如何處理 `EADDRINUSE` 錯誤