socket.io, how do I get the event name from within the function?

Question

socket.io, how do I get the event name from within the function?

in node.js and socket.io, many events can be handled by one function:

socket.on( 'async.popular_qtns', rows.bind(socket) );
socket.on( 'async.recent_qtns', rows.bind(socket) );
socket.on( 'async.enum_chn', rows.bind(socket) );
socket.on( 'async.enum_tag', rows.bind(socket) );

function rows() {
  var socket = this;
  switch( socket.?? ) {
    case 'async.popular_qtns': // blah blah
        break;
    case 'async.recent_qtns': // blah blah
        break;
  }
}

how do I get the event name, eg, 'async.enum_tag' associated with the socket.on()?

javascript
node.js
socket.io

Answer 1

I don't think the event name is reported to the callback function. You could try something like this:

var rowsBound = rows.bind(socket);

socket.on( 'async.popular_qtns', function() { rowsBound('asyn.popular_qtns'); } );
socket.on( 'async.recent_qtns', function() { rowsBound('asyn.recent_qtns'); } );
socket.on( 'async.enum_chn', function() { rowsBound('asyn.enum_chn'); } );
socket.on( 'async.enum_tag', function() { rowsBound('asyn.enum_tag'); } );

Or, probably better:

var rowsBound = rows.bind(socket),
    events = ['async.popular_qtns', 'async.recent_qtns', 'async.enum_chn', 'async.enum_tag'];

for (var i in events)
    (function(e) { socket.on(e, function() { rowsBound(e); }); })(events[i]);

Answer 2

Also, you may use express.io with express.io-middleware, which adds req.io.event, which store event name and req.io.namespaces which store first part of event name, splitted by ':'.