Can Connection#send() throw an error?

[ibc]

If I call send() or sendUTF() or sendBytes() on an already closed Connection, or if sending fails due to connection error, would it throw an error?

It is not documented.

[theturtle32]

No. The behavior for this is inherited from the Socket implementation in Node core. If there is an error, such as when writing to a closed socket, it will emit an error event on nextTick. I believe earlier versions of Node did throw in some cases, so I used to normalize that behavior using try/catch, but that's not necessary anymore because Node never throws when calling write except when the user calls it with invalid parameters.

The main difference here is that if nobody is listening for an error event on the WebSocketConnection instance, it will silently swallow the error event instead of letting it bubble up and crash the application. My reasoning for that was that it will actually be pretty common to run into these errors in production, and it will immediately trigger a close event, and there's no other handling that needs to be done by the user for these errors. I do expose the error event for anyone who finds it useful in their particular situation, but if no listeners are added for the error event, then any error events emitted by the underlying Socket will be silently discarded.

See io.js/net.js - writeAfterFIN

See also WebSocketConnection.prototype.handleSocketError

[theturtle32]

Should I add a comment to the documentation to this effect?

[ibc]

Thanks for the explanation! Yes, I would find some text about this subject really useful in the API doc :)