Electron Auto WebSocket Port Retry

The idea: store an initial port in a local config.json. Each startup tries to bind the WebSocket server; if the port is occupied, increment the port in config.json, save, relaunch Electron until a free port is found.

Example config:

{"port":1081}

Code snippet:

const { app, BrowserWindow, dialog } = require("electron");
const WebSocket = require("ws");
const fs = require("fs");
let wss = {};
openWs();
function openWs() {
  fs.readFile("config.json", "utf-8", (err, configFileDataRes) => {
    if (err) {
      dialog.showMessageBox({
        type: "info",
        title: "Read config failed",
        message: "Please reinstall",
        detail: JSON.stringify(err),
      });
      throw err;
    }
    const configFileData = JSON.parse(configFileDataRes);
    try {
      wss = new WebSocket.Server({ port: configFileData.port });
    } catch (error) {
      console.log("Create WebSocket failed:", error);
    }
    wss.on("connection", (ws) => {
      console.log(configFileData.port + " connected");
      ws.on("message", (message) => {
        message = JSON.parse(message);
        if (message.type == "open_page") {
          const win = new BrowserWindow();
          win.loadFile(message.src);
          win.webContents.openDevTools({ mode: "detach" });
          if (message.big) win.maximize();
        }
      });
      ws.send("ok");
    });
    wss.on("error", () => {
      storeData({ port: parseInt(configFileData.port) + 1 }, "config.json");
      app.exit();
      app.relaunch();
    });
  });
}