Streaming Price of Bitcoin from FTX> https://docs.ftx.com/#websocket-api

fix_stream_price.js

import WebSocket from 'ws';
const ws = new WebSocket('wss://ftx.com/ws/');

let ping;
function open() {
  ws.on('open', function open() {
    ws.send(JSON.stringify({
      op: 'subscribe', 
      channel: 'ticker',
      market: 'BTC-PERP'
    }))

    setInterval(() => {
      if (ping === "yes")
        open();

      ping = "yes";
      ws.send(JSON.stringify({ op: 'ping' }))
    }, 15000);
  });
}
open();

ws.on('message', async (data) => {
  let payload
  try {
    payload = JSON.parse(data);
  } catch(e) {
    console.error('ftx send bad json', data);
  }

  if (payload)
  {
    if (payload.channel === "ticker" && payload.type === "update")
      priceData = payload.data; 
    else if (payload.type === "pong")
      ping = "done";
  } 
});

ws.on('error', (error) => {
  console.error(error);
});