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(timestamp(), '::SimplyWS:: 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(), 35000);
        };
        client.on('ping', () => {
            console.log(timestamp(), '::SimplyWS:: pinged');
            heartbeat();
        });
        client.on('open', (e) => {
            if (typeof this.onOpen === 'function') {
                this.onOpen();
            } else {
                console.log(timestamp(), '::SimplyWS:: opened');
                console.log(e);
            }
            heartbeat();
        });
        client.on('message', (e) => {
            if (typeof this.onMessage === 'function') {
                this.onMessage(e);
            } else {
                console.log(timestamp(), '::SimplyWS:: 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(timestamp(), '::SimplyWS:: 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(timestamp(), '::SimplyWS : errored');
                console.error(e);
            }
        });
        this.send = client.send.bind(client);
    };
    init();
}

module.exports = WebSocketClient;