Socket.io client does not connect to server

Question

I am trying to make a Node.js app that will have an embedded chat. I am using socket.io to create that chat. I have attempted to set up my server / client, but the client does not seem to be connecting. I have my application to set log when sockets connect and disconnect but it never seems to log anything. I figured that the client was being retarded so I opened the Chrome devtools, and typed in:

var socket = io();

oddly, I start seeing a string of failed requests that look like:

GET http://localhost:3000/socket.io/?EIO=3&transport=polling&t=1434334401655-37 404 (Not Found)

So now I'm sure it s my server. here is my server code:

var express = require("express");
var mongoose = require("mongoose");
var io = require("socket.io").listen(app);
// var restAPI = require("./api");

// Set up the application.
var app = express();
app.use(express.static("static"));

// Mount up the rest API
// app.use("/rest", restAPI);

// Default index route.
app.get("/", function(req, res) {
    res.sendFile(__dirname + "/index.html");
});

// This will maintian a transcript of the chat
var transcript = []

// This route will return the transcript data as json
app.get("/transcript", function(req, res) {
    res.json(JSON.stringify(transcript));
});

// Simple socket.io for chat application 
// Lets keep a reference to how many connections we have
var count = 0;
io.sockets.on("connection", function(socket) {
    // Increment the number of clients
    count++
    // Keep a reference to the socket
    var current = socket;
    // Log the connection
    console.log("Connected to: " + current + " at " + Date.now() + ".");
    // Log the current number of users
    console.log("There are now " + count + "users connected.");

    // Handle disconnection
    socket.on("disconnect", function() {
        // Same routine as connect
        console.log(current + ": disconnected at " + Date.now() + ".");
        console.log("There are now " + count + "users connected.");
    });
});

app.listen(3000);

Here is my HTML client:

<!DOCTYPE html>
<html>
    <head>
        <meta name="viewport">
        <title>Paint</title>
        <!-- <script src="/js/application.js"></script> -->
        <script src="https://cdn.socket.io/socket.io-1.3.5.js"></script>
    </head>
    <body>
        <header></header>
        <nav></nav>
        <aside>
            <div id="toolbox"></div>
            <!-- display: none; by default -->
            <div id="chat"></div>

            <div class="buttons">
                <div class="toolBoxButton">Toolbox</div>
                <div class="chatButton">Chat</div>
            </div>
        </aside>
        <section></section>
        <footer></footer>
        <script>
            var socket = io();
        </script>
    </body>
</html>

Why can't the client connect?

jfriend00 · Accepted Answer · 2015-06-15 02:25:04Z

1

I don't know if this is the only issue, but you're calling this:

var io = require("socket.io").listen(app);

before you assign the app variable so it is undefined.

The request for this URL:

http://localhost:3000/socket.io/?EIO=3&transport=polling&t=1434334401655-37

is how a socket.io connection starts so that is normal. The problem is that the socket.io listener wasn't running properly on the server so nothing was listening for that route.

Also, I don't know if this:

io.sockets.on("connection", function(socket) {...});

works in socket.io v1+. The socket.io doc says to use this:

io.on('connection', function(socket) {...});

edited Jun 15, 2015 at 2:25

answered Jun 15, 2015 at 2:19

jfriend00

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3 Comments

James Parsons Over a year ago

Changing io.sockets.on to io.on didn't change anything. So I tried to change where I connected. I tried to put io.listen(app); right before the connection event handler, but then it tells me I can;t connect socket.io to an express app to connect it to a http.Server instead. So i try io.listen(http.createServer(app));, then I Undefined is not a function on io.on.

jfriend00 Over a year ago

@James_Parsons - I can't follow what you tried without seeing the whole sequence of code. Why don't you just follow the instructions here: socket.io/docs? It's all spelled out there. You will need to know what version of socket.io and what version of Express to know which instructions to follow.

James Parsons Over a year ago

@jfiriend00 thanks for that link. I was trying to create an HTTP server in the wring way. Wow Node.js stuff outdated quickly!

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