WebsocketSample.js

/**
 *  Node.js example 
 *  https://github.com/Bittrex/beta
 *
 *  Adrian Soluch
 *
 *  prerequisites:
 *  npm i signalr-client jsonic
 *
 *  tested with node v9.10.1
 */
const signalR = require ('signalr-client');
const jsonic = require('jsonic');
const zlib = require('zlib');

const client  = new signalR.client (
  'wss://beta.bittrex.com/signalr',
  ['c2']
);

let market = 'BTC-ETH',
    data,
    b64,
    raw,
    json;

client.serviceHandlers.connected = function (connection) {
  console.log ('connected');
  client.call ('c2', 'SubscribeToExchangeDeltas', market).done (function (err, result) {
    if (err) { return console.error (err); }
    if (result === true) {
      console.log ('Subscribed to ' + market);
    }
  });
}

client.serviceHandlers.messageReceived = function (message) {
  data = jsonic (message.utf8Data);
  if (data.hasOwnProperty ('M')) {
    if (data.M[0]) {
      if (data.M[0].hasOwnProperty ('A')) {
        if (data.M[0].A[0]) {
          /**
           *  handling the GZip and base64 compression
           *  https://github.com/Bittrex/beta#response-handling
           */
          b64 = data.M[0].A[0];
          raw = new Buffer.from(b64, 'base64');

          zlib.inflateRaw (raw, function (err, inflated) {
            if (! err) {
              json = JSON.parse (inflated.toString ('utf8'));
              console.log (json);
            }
          });
        }
      }
    }
  }
};