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

If you use async/await and you just want to wait until the connection is available I would suggest this function :

async connection (socket, timeout = 10000) {
  const isOpened = () => (socket.readyState === WebSocket.OPEN)

  if (socket.readyState !== WebSocket.CONNECTING) {
    return isOpened()
  }
  else {
    const intrasleep = 100
    const ttl = timeout / intrasleep // time to loop
    let loop = 0
    while (socket.readyState === WebSocket.CONNECTING && loop < ttl) {
      await new Promise(resolve => setTimeout(resolve, intrasleep))
      loop++
    }
    return isOpened()
  }
}

Usage (in async function) :

const websocket = new WebSocket('...')
const opened = await connection(websocket)
if (opened) {
  websocket.send('hello')
}
else {
  console.log("the socket is closed OR couldn't have the socket in time, program crashed");
  return
}