socket.io emits multiple times

For the client side you can use socket.once() instead of socket.on(). Example:

socket.once('result', function(data){
 console.log('The data is '+data)
})

Reference: https://socket.io/docs/v3/listening-to-events/#socket-once-eventName-listener

I didn't read the question, but I'm putting this on here to help the others, cause I hadn't find this kind of answer yet.

In my case, I was calling the function next multiple times, just like so

io.use(async (socket, next) => {
    let req = socket.request
    let res = req.res || {}

    someMiddleware()(req, res, next)
    anotherMiddleware({extended: false})(req, res, next)
    anotherMiddleware()(req, res, next)
    anotherMiddleware(req, res, next)
    anotherMiddleware()(req, res, next)
    anotherMiddleware()(req, res, next)
})

Every time I was calling a middleware, the next function was getting called and on('connection') was being called too. What I got to do was overwrite the next and put it inside the last middleware, so connection get called just once.

. . .
let originalNext = next
next = () => {} // NOW its not going to annoy anymore
someMiddleware()(req, res, next)
anotherMiddleware({extended: false})(req, res, next)
anotherMiddleware()(req, res, next)
anotherMiddleware(req, res, next)
anotherMiddleware()(req, res, next)
anotherMiddleware()(req, res, originalNext) //next get called <
. . .

I think you are adding more and more listeners to 'result' each call you make to check.

First time click -> call 1 console.log from call 1 listener

Second time click -> call 1 console.log from call 1 listener + call 2 console.log from call 1 listener + call 2 console.log from call 2 listener

Third time -> The previous logs + call 3 console.log from call 1 listener + call 3 console.log from call 2 listener and call 3 console.log from call 3 listener.

Try putting the listener for 'result' out of the function:

<html>
 <body>
    <button onclick="check()">Test Me :-)</button>
    <script src="/socket.io/socket.io.js"></script>
    <script>
      var socket = io.connect('http://localhost:3000');

       socket.on('result', function(data){
            console.log('The data is '+data)
        })
      var check = function(){

        var data = { id : '234'};
        socket.emit('chat', data);
      }
    </script>
 </body>
</html>

socket.io emits multiple times

Tags:

Node.Js

Express

Socket.Io

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