如何检测未注册的socket.io事件？

Question

I'm using node.js and socket.io for a chat program and I listen to some events. Here is the relevant code:

server: io.sockets.on('connection',( socket ) => {
    socket.on('joinRoom',( data )=>{ do with message });
    socket.on('leaveRoom',( data )=>{ do with message });
}
client: io.emit('joinRoom',{uid:11});

If the client emits an event which is not registered as io.emit('noEvent',{}); , how does the server detect it?

Answer 1

Use socketio-wildcard plugin.

You can use the wildcard plugin for socket IO to do that as suggested in SocketIO official documentation here , like so:

socket.on('*', function(packet){
  // client.emit('foo', 'bar', 'baz')
  packet.data === ['foo', 'bar', 'baz']
});

Answer 2

Because the socket server is listening for something to happen on the port not the 'event'. So if something is 'emitted' and there is a 'listener' it will pick that up, it just won't know exactly what to do with it.

Not sure if this will help but here is the socket.io cheetsheet

Answer 3

In 3.x, it can be done without any plugins using onAny listener :

socket.onAny((eventName, ...args) => {
  const isNotRegistered = !Object.keys(socket._events).includes(eventName)
  
  if (isNotRegistered) {
    // Event is not registered
  }
})