samol samol - 1 year ago 593
Javascript Question

WebSocket: How to automatically reconnect after it dies

var ws = new WebSocket('ws://localhost:8080');
ws.onopen = function () {
ws.send(JSON.stringify({
.... some message the I must send when I connect ....
}));

};

ws.onmessage = function (e) {
console.log('Got a message')
console.log(e.data);
};

ws.onclose = function(e) {
console.log('socket closed try again');

}

ws.onerror = function(err) {
console.error(err)
};


When I first connect to the socket, I must first send a message to the server to authenticate myself and subscribe to channels.

The problem I have is that sometimes the socket server is unreliable and that triggers the
onerror
and
onclose
events of the
'ws'
object.

Question: What is a good design pattern that would allow me, whenever the socket closes or encounters an error, wait for 10 seconds and then reconnect to the socket server (and resend the initial message to the server)

Answer Source

Here is what I ended up with. It works for my purposes.

function connect() {
  var ws = new WebSocket('ws://localhost:8080');
  ws.onopen = function() {
    // subscribe to some channels
    ws.send(JSON.stringify({
        //.... some message the I must send when I connect ....
    }));
  };

  ws.onmessage = function(e) {
    console.log('Message:', e.data);
  };

  ws.onclose = function(e) {
    console.log('Socket is closed. Reconnect will be attempted in 1 second.', e.reason);
    setTimeout(function() {
      connect();
    }, 1000);
  };

  ws.onerror = function(err) {
    console.error('Socket encountered error: ', err.message, 'Closing socket');
    ws.close();
  };
}

connect();
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