Quick and dirty draft of a reconnecting websocket with connecting timeout

websocket-reconnect.js

/**
 * Quick and dirty draft of a reconnecting websocket with connecting timeout
 */

console.debug('script init')


const MAX_RECONNECTION_DELAY = 8000
const MIN_RECONNECTION_DELAY = 1500
const CONNECTING_TIMEOUT = 5000
const RECONNECTION_DELAY_MULTIPLIER = 1.3

let reconnectDelay = 0
let ws

const initReconnectDelay = () => {
    reconnectDelay = MIN_RECONNECTION_DELAY + Math.random() * MIN_RECONNECTION_DELAY
    console.debug('init reconnect delay:', reconnectDelay)
}

const updateReconnectionDelay = () => {
    reconnectDelay *= RECONNECTION_DELAY_MULTIPLIER
    if (reconnectDelay > MAX_RECONNECTION_DELAY) {
        reconnectDelay = MAX_RECONNECTION_DELAY
    }
    console.debug('update reconnect delay:', reconnectDelay)
}

const connect = () => {

    ws = new WebSocket('ws://localhost:8080')

    const connectingTimeout = setTimeout(() => {
        console.debug('connecting timeout:', CONNECTING_TIMEOUT)
        ws.close()
    }, CONNECTING_TIMEOUT)

    ws.onmessage = (ev) => console.debug('>', ev.data)

    ws.onclose = (ev) => {
        console.debug('close:', ev)
        if (!reconnectDelay) {
            initReconnectDelay()
        } else {
            updateReconnectionDelay()
        }
        setTimeout(connect, reconnectDelay)
    }

    ws.onerror = (ev) => console.debug('error:', ev)

    ws.onopen = (ev) => {
        initReconnectDelay()
        clearTimeout(connectingTimeout)
        console.debug('open:', ev)
    }
}

connect()

Simple ws echo server for testing previous code

• Requires ws: npm install ws
• Send crash to crash the server
• Send hang to hang the server

const WebSocketServer = require('ws').Server
const wss = new WebSocketServer({port: 8080})
wss.on('connection', (ws) => {
  ws.on('message', (message) => {
    console.log('received: %s', message)
    if (message === 'crash') {
        throw Error('crash')
    }
    if (message === 'hang') {
        while (true) {}
    }
    ws.send(message)
  })
  ws.send('hello')
})