Web socket exception could not be caught

Question

When I intentionally shut down a web sockets server the client JavaScript code:

try
{
    self.socket.send('ping');
}
catch(ex)
{
    console.log('exception');
}

writes in Chrome console:

WebSocket is already in CLOSING or CLOSED state.

This exception couldn't be caught by try-catch. How to detect for sure that data could not be sent through web socket? onclose event is not being fired.

score 1 · Accepted Answer · answered Aug 08 '14 at 09:04

I reconciled myself to the fact that the error couldn't be caught and implemented a ping-pong solution.

JavaScript sends each n seconds a 'ping' command and server should respond with 'pong'. If more than 5 'pings' were sent without response, reconnect is initiated.

score 1 · Answer 2 · answered Dec 15 '15 at 18:19

1

You can check the readyState.

try
{
  if (self.socket && self.socket.readyState === 1) {
    self.socket.send('ping');
  }
  else {
    throw(new Error("WebSocket is not in OPEN state."));
  }
}
catch(ex)
{
  console.log('exception', ex);
}

answered Dec 15 '15 at 18:19

Ignacio Lago

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Web socket exception could not be caught

2 Answers2