使用 socket.io 每隔几秒以编程方式触发一个事件

Question

My server wants to say "hi" to the clients every interval of time. I have this example of code to demonstrate the event firing according to interval of time. But sadly it is not working.

server:

    var app = require('http').createServer(handler),
     io = require('socket.io').listen(app),
     fs = require('fs');


    app.listen(8001);



     function handler(req, res) {
     fs.readFile(__dirname + '/client1.html', function(err, data) {
      if (err) {
      console.log(err);
      res.writeHead(500);
      return res.end('Error loading client1.html');
    }
    res.writeHead(200);
      res.end(data);
    });
  }

  io.sockets.on('connection', function (socket) {
    console.log("runing time");

    socket.emit( "clientMessage","hi from server");
    socket.on('clientMessage', function () {
        socket.emit( "serverMessage","hi from server");
    });
    socket.on('disconnect', function () {
        console.log("disconnecting");
    });
  });

Client:

   <script src="/socket.io/socket.io.js"></script>

   <script>
   var socket = io.connect("http://localhost:8001");
   socket.on('connection', function(socket) {


       // *this line is not reached*
        alert("connected")

      sendTestMessage()

    socket.on("serverMessage", function(d) {
        alert("server Message : " + d)
    })
    socket.on('disconnect', function() {
        alert("disconnected")
    });

   });


   function sendTestMessage() {
    alert("test")
    socket.emit('clientMessage', "Test Message From Client");
    setTimeout(sendTestMessage(), 5000)
   }

  </script>

Please any help why?

Answer 1

I think the problem may be here:

setTimeout(sendTestMessage(), 5000)

Looks like you are calling the function, but just need to pass a reference instead.

Try:

setTimeout(sendTestMessage, 5000);

Answer 2

events on server side and client side should be same. you should try this server.js:

io.on('connection', function (socket) {
console.log("runing time");

setInterval(()=>{
socket.emit("clientMessage","hi from server")
}, 1000)

socket.on('disconnect', function () {
    console.log("disconnecting");
});

client.js:

socket.on('connect',()=>{console.log('socket connected')});

socket.on('disconnect',()=>{console.log('socket disconnected')});

socket.on('clientMessage', (msg)=>{
   console.log('Message From Server: ', msg)
});

this will emit message from server after every second to client.