server.js

/* eslint-env node */
/* eslint-disable no-console */
const http = require("http");
const WebSocketServer = require("websocket").server;

const port = 8081;

const server = http.createServer(function (request, response) {
  console.log(`${new Date()} Received request for ${request.url}`);
  response.writeHead(404);
  response.end();
});

server.listen(port, function () {
  console.log(`${new Date()} Server is listening on port ${port}`);
});

const wsServer = new WebSocketServer({
  httpServer: server,
  autoAcceptConnections: false,
});

const pingInterval = 2000;

wsServer.on("request", (request) => {
  const connection = request.accept(
    request.requestedProtocols[0],
    request.origin
  );

  console.log("Connection accepted");
  let pingCount = 0;

  const interval = setInterval(() => {
    pingCount += 1;
    connection.send(JSON.stringify({ type: "ping", event: { pingCount } }));
  }, pingInterval);

  connection.on("close", () => {
    clearInterval(interval);
  });
});