sync-pk-sp/WebsocketClient.js

const WebSocket = require('ws')
const timestamp = () => new Date().toISOString().replace('T', ' ').substr(0, 19)

function WebSocketClient(url) {
    let client
    let timeout
    let connecting = false
    let backoff = 250
    const init = () => {
        console.error(`::SimplyWS:: [${timestamp()}] connecting`)
        connecting = false
        if (client !== undefined) {
            client.removeAllListeners()
        }
        client = new WebSocket(url)
        const heartbeat = () => {
            if (timeout !== undefined) {
                clearTimeout(timeout)
                timeout = undefined
            }
            timeout = setTimeout(() => client.terminate(), 350000)
        }
        client.on('ping', () => {
            console.log(`::SimplyWS:: [${timestamp()}] pinged`)
            heartbeat()
        })
        client.on('open', (e) => {
            if (typeof this.onOpen === 'function') {
                this.onOpen()
            } else {
                console.log(`::SimplyWS:: [${timestamp()}] opened`)
                console.log(e)
            }
            heartbeat()
        })
        client.on('message', (e) => {
            if (typeof this.onMessage === 'function') {
                this.onMessage(e)
            } else {
                console.log(`::SimplyWS:: [${timestamp()}] messaged`)
            }
            heartbeat()
        })
        client.on('close', (e) => {
            if (e.code !== 1000) {
                if (connecting === false) { // abnormal closure
                    backoff = backoff === 8000 ? 250 : backoff * 2
                    setTimeout(() => init(), backoff)
                    connecting = true
                }
            } else if (typeof this.onClose === 'function') {
                this.onClose()
            } else {
                console.error(`::SimplyWS:: [${timestamp()}] closed`)
                console.error(e)
            }
        })
        client.on('error', (e) => {
            if (e.code === 'ECONREFUSED') {
                if (connecting === false) { // abnormal closure
                    backoff = backoff === 8000 ? 250 : backoff * 2
                    setTimeout(() => init(), backoff)
                    connecting = true
                }
            } else if (typeof this.onError === 'function') {
                this.onError(e)
            } else {
                console.error(`::SimplyWS:: [${timestamp()}] errored`)
                console.error(e)
            }
        })
        this.send = client.send.bind(client)
    }
    init()
}

module.exports = WebSocketClient