const ws = require('ws')
const w = new ws('wss://api-pub.bitfinex.com/ws/2')

w.on('message', (msg) => console.log(msg))

let msg = JSON.stringify({ 
  event: 'subscribe', 
  channel: 'ticker', 
  symbol: 'tBTCUSD' 
})

w.on('open', () => w.send(msg))

wscat -c wss://api-pub.bitfinex.com/ws/2
{ "event": "subscribe",  "channel": "ticker",  "symbol": "tBTCUSD" }

ws = websocket.WebSocketApp('wss://api-pub.bitfinex.com/ws/2')

ws.on_open = lambda self: self.send('{ "event": "subscribe", "channel": "ticker", "symbol": "tBTCUSD"}')

ws.on_message = lambda self, evt:  print (evt)

// request
{ 
  event: "subscribe", 
  channel: "ticker", 
  symbol: SYMBOL
}

// response - trading
{
   event: "subscribed",
   channel: "ticker",
   chanId: CHANNEL_ID,
   symbol: SYMBOL,
   pair: PAIR
}

{"event":"subscribed","channel":"ticker","chanId":224555,"symbol":"tBTCUSD","pair":"BTCUSD"}

// response - funding
{
  event: "subscribed",
  channel: "ticker",
  chanId: CHANNEL_ID,
  symbol: SYMBOL,
  currency: CURRENCY
}

{"event":"subscribed","channel":"ticker","chanId":232591,"symbol":"fUSD","currency":"USD"}

// Trading pairs

[
  443378, //CHANNEL_ID
  [
    7616.5, //BID
    31.89055171, //BID_SIZE
    7617.5, //ASK
    43.358118629999986, //ASK_SIZE
    -550.8, //DAILY_CHANGE
    -0.0674, //DAILY_CHANGE_RELATIVE
    7617.1, //LAST_PRICE
    8314.71200815, //VOLUME
    8257.8, //HIGH
    7500 //LOW
  ] //UPDATE
]

// Funding pairs

[
  234509, //CHANNEL_ID
  [
    0.0003193369863013699, //FRR
    0.0002401, //BID
    30, //BID_PERIOD
    3939629.6177260396, //BID_SIZE
    0.00019012, //ASK
    2, //ASK_PERIOD
    307776.1592138799, //ASK_SIZE
    -0.00005823, //DAILY_CHANGE
    -0.2344, //DAILY_CHANGE_RELATIVE
    0.00019016, //LAST_PRICE
    122156333.45260866, //VOLUME
    0.00027397, //HIGH
    6.8e-7, //LOW
    null, //PLACEHOLDER
    null, //PLACEHOLDER
    3441851.73330503 //FRR_AMOUNT_AVAILABLE
  ] //UPDATE
]

// Trading pairs

[
  443378, //CHANNEL_ID
  [
    7616.5, //BID
    31.89055171, //BID_SIZE
    7617.5, //ASK
    43.358118629999986, //ASK_SIZE
    -550.8, //DAILY_CHANGE
    -0.0674, //DAILY_CHANGE_RELATIVE
    7617.1, //LAST_PRICE
    8314.71200815, //VOLUME
    8257.8, //HIGH
    7500 //LOW
  ] //UPDATE
]

// Funding pairs

[
  234509, //CHANNEL_ID
  [
    0.0003193369863013699, //FRR
    0.0002401, //BID
    30, //BID_PERIOD
    3939629.6177260396, //BID_SIZE
    0.00019012, //ASK
    2, //ASK_PERIOD
    307776.1592138799, //ASK_SIZE
    -0.00005823, //DAILY_CHANGE
    -0.2344, //DAILY_CHANGE_RELATIVE
    0.00019016, //LAST_PRICE
    122156333.45260866, //VOLUME
    0.00027397, //HIGH
    6.8e-7, //LOW
    null, //PLACEHOLDER
    null, //PLACEHOLDER
    3441851.73330503 //FRR_AMOUNT_AVAILABLE
  ] //UPDATE
]

Request fields

Fields	Type	Description
SYMBOL	String	Trading pair or funding currency

Stream data

Index	Field	Type	Description
[0]	CHANNEL_ID	Int	Identification number assigned to the channel for the duration of this connection.
[1]	UPDATE	Array	Array with relevant data (trading snapshot/update or funding snapshot/update)

Trading snapshot/update (Index [1])

Index	Field	Type	Description
[0]	BID	Float	Price of last highest bid
[1]	BID_SIZE	Float	Sum of the 25 highest bid sizes
[2]	ASK	Float	Price of last lowest ask
[3]	ASK_SIZE	Float	Sum of the 25 lowest ask sizes
[4]	DAILY_CHANGE	Float	Amount that the last price has changed since yesterday
[5]	DAILY_CHANGE_RELATIVE	Float	Relative price change since yesterday (*100 for percentage change)
[6]	LAST_PRICE	Float	Price of the last trade.
[7]	VOLUME	Float	Daily volume
[8]	HIGH	Float	Daily high
[9]	LOW	Float	Daily low

Funding snapshot/update (Index [1])

Index	Field	Type	Description
[0]	FRR	Float	Flash Return Rate - average of all fixed rate funding over the last hour (funding tickers only)
[1]	BID	Float	Price of last highest bid
[2]	BID_PERIOD	Int	Bid period covered in days (funding tickers only)
[3]	BID_SIZE	Float	Sum of the 25 highest bid sizes
[4]	ASK	Float	Price of last lowest ask
[5]	ASK_PERIOD	Int	Ask period covered in days (funding tickers only)
[6]	ASK_SIZE	Float	Sum of the 25 lowest ask sizes
[7]	DAILY_CHANGE	Float	Amount that the last price has changed since yesterday
[8]	DAILY_CHANGE_RELATIVE	Float	Relative price change since yesterday (*100 for percentage change)
[9]	LAST_PRICE	Float	Price of the last trade.
[10]	VOLUME	Float	Daily volume
[11]	HIGH	Float	Daily high
[12]	LOW	Float	Daily low
[ . . . ]
[15]	FRR_AMOUNT_AVAILABLE	Float	The amount of funding that is available at the Flash Return Rate (funding tickers only)