为什么socket.emit不从客户端到服务器发出包？

Question

I'm trying to set up a sign in system for my server, but the socket.emit function doesn't seem to be working. I'm using socket.io and express.

I made sure that there were no errors, there were no errors according to the Chrome developer tab or the command prompt which I'm using as a console for the server.

   var io = require('socket.io')(serv, {});
   var socket = io();

   socket.on('signIn', function (data) {
        console.log('Sign In Request')
    });


   // client

    signInButton.onclick = function () {
                socket.emit('signIn', { 
                    username: signInUsername.value, 
                    password: signInPassword.value 
                });

When I click the button, nothing gets logged to console.

I expect the message "Sign In Request" to be logged to console when I click on the button (signInButton). They are all defined, and I don't know why it doesn't.

Answer 1

When writing server-side socket event handling, you need to interact with specific socket objects, after you detect their connection. Like so:

// server
const SocketIO = require('socket.io');
const io = SocketIO(serv);

io.on('connection', (socket) => {
  socket.on('signIn', (obj) => {
    // obj.username / obj.password
  });
});