in node.js / socket.io, how to tell if an object is an instanceof a socket?

Question

in node.js / socket.io, how to tell if an object is an instanceof a socket?

in my app the socket is passed around as this using bind and call

socket.on( 'handle', someFunc.bind(socket) );

function someFunc() {
  var socket = this;
  ...
  anotherFunc.call( socket, 'abc', ... );
}

I wish to ensure that this is indeed a socket - forgetting - using func(...) instead of func.call(socket,...).

function someFunc() {
  var socket = this;
  assert.ok( /* ensure this is instanceof a socket */ );
  ...
}

how do I make the assertion?

is there some socket within io = require('socket.io') that I can use?

javascript
node.js
socket.io

Answer 1

To solve the specific problem in question, it is probably better to check whether this is not null:

function someFunc() {
  var socket = this;
  assert.ok(socket);
  ...
}

The assert will fail for someFunc(); call, and will only pass for someFunc.bind(socket)(); and someFunc.call(socket); calls (as long as socket is not null).

Relying on the implementation details, as Bergi suggested, will render your application unusable should the next Node.js version feature a different implementation; and it does not seem to be a part of the public API.

Answer 2

From what I read in the source, it returns a Manager instance. This check should work:

var io = require('socket.io');
var socket = io.listen(...);

socket instanceof io.Manager; // true