Socket.io Client: respond to all events with one handler?

Question

Is it possible to have a socket.io client respond to all events without to have specify each event individually?

For example, something like this (which obviously do

Answer 1

Here you go ...

var socket = io.connect();
var globalEvent = "*";
socket.$emit = function (name) {
    if(!this.$events) return false;
    for(var i=0;i<2;++i){
        if(i==0 && name==globalEvent) continue;
        var args = Array.prototype.slice.call(arguments, 1-i);
        var handler = this.$events[i==0?name:globalEvent];
        if(!handler) handler = [];
        if ('function' == typeof handler) handler.apply(this, args);
        else if (io.util.isArray(handler)) {
            var listeners = handler.slice();
            for (var i=0, l=listeners.length; i<l; i++)
                listeners[i].apply(this, args);
        } else return false;
    }
    return true;
};
socket.on(globalEvent,function(event){
    var args = Array.prototype.slice.call(arguments, 1);
    console.log("Global Event = "+event+"; Arguments = "+JSON.stringify(args));
});

This will catch events like connecting, connect, disconnect, reconnecting too, so do take care.

Answer 2

As it is in v3.0 documentation:

socket.onAny((event, ...args) => {
  console.log(`got ${event}`);
});

Answer 3

Note: this answer is only valid for socket.io 0.x

You can override socket.$emit

With the following code you have two new functions to:

• Trap all events
• Trap only events which are not trapped by the old method (it is a default listener)

var original_$emit = socket.$emit;
socket.$emit = function() {
    var args = Array.prototype.slice.call(arguments);
    original_$emit.apply(socket, ['*'].concat(args));
    if(!original_$emit.apply(socket, arguments)) {
        original_$emit.apply(socket, ['default'].concat(args));
    }
}

socket.on('default',function(event, data) {
    console.log('Event not trapped: ' + event + ' - data:' + JSON.stringify(data));
});

socket.on('*',function(event, data) {
    console.log('Event received: ' + event + ' - data:' + JSON.stringify(data));
});

Answer 4

Because your question was pretty general in asking for a solution, I'll pitch this one that requires no hacking the code, just a change in how you use the socket.

I just decided to have my client app send the exact same event, but with a different payload.

socket.emit("ev", { "name" : "miscEvent1"} );
socket.emit("ev", { "name" : "miscEvent2"} );

And on the server, something like...

socket.on("ev", function(eventPayload) {
   myGenericHandler(eventPayload.name);
});

I don't know if always using the same event could cause any issues, maybe collisions of some kind at scale, but this served my purposes just fine.

Answer 5

The current (Apr 2013) GitHub doc on exposed events mentions a socket.on('anything'). It appears that 'anything' is a placeholder for a custom event name, not an actual keyword that would catch any event.

I've just started working with web sockets and Node.JS, and immediately had a need to handle any event, as well as to discover what events were sent. Can't quite believe this functionality is missing from socket.io.

Answer 6

socket.io-client 1.7.3

As of May 2017 couldn't make any of the other solutions work quite how i wanted - made an interceptor, using at Node.js for testing purposes only:

var socket1 = require('socket.io-client')(socketUrl)
socket1.on('connect', function () {
  console.log('socket1 did connect!')
  var oldOnevent = socket1.onevent
  socket1.onevent = function (packet) {
    if (packet.data) {
      console.log('>>>', {name: packet.data[0], payload: packet.data[1]})
    }
    oldOnevent.apply(socket1, arguments)
  }
})

References:

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply
• https://github.com/socketio/socket.io-client/blob/ff4cb3eed04a95c9725b8aaba8b64fa9fa1ca413/lib/socket.js#L257