How to wait for a WebSocket's readyState to change

Question

I\'m trying to implement a WebSocket with a fallback to polling. If the WebSocket connection succeeds, readyState becomes 1, but if it fails, readyState

Answer 1

Just like you defined an onmessage handler, you can also define an onerror handler. This one will be called when the connection fails.

var socket = new WebSocket(url);
socket.onmessage = onmsg;
socket.onerror = function(error) {
    // connection failed - try polling
}