When trying to request the last candle to bitfinex i ended up doing the following request:

https://api-pub.bitfinex.com/v2/candles/trade:1D:tBTCUSD/hist?limit=5000&start=1671062400000&end=1671062400000

I can see bitfinex answers very quick in the browser with:

[
  "error",
  10020,
  "time_interval: invalid"
]

But on my jest test it was timing out because it was taking more than 5000 ms to resolve the request.

I wonder if tvcd will keep retrying to request and for that reason the timeout happens?

Vercel has a very nice library to convert string "timeframe" to number and vice-versa, we could potentially use it to do timeframe conversions where needed: https://github.com/vercel/ms

This article explain some interesting concepts on unin type VS enum

From some tests i did, string union type provide a better autocomplete experience on VSCode when filling function parameters ( as an end user ).

So when calling functions users can directly type the string value ( and see all options listed on VSCode ) instead of having to import the Enum and use the Enum.

Of course that's a minor detail in implementation, so low priority..

In case that would be implemented we would have an enum like that

export enum Exchanges {
  'binance' = 'binance',
  'binancefuturescoin' = 'binancefuturescoin',
  'binancefuturesusd' = 'binancefuturesusd',
  'bitfinex' = 'bitfinex',
  'bitmex' = 'bitmex',
  'bittrex' = 'bittrex',
  'deversifi' = 'deversifi',
  'gateio' = 'gateio',
  'kucoin' = 'kucoin',
  'poloniex' = 'poloniex',
  'valr' = 'valr',
}

But function arguments that require exchange names as parameters would have type Exchanges instead of ExchangesEnum

export type Exchanges = 
  'binance' | 
  'binancefuturescoin' | 
  'binancefuturesusd' |
  ...

Today i accidentally tried to ask for 3H candle instead of 3h candle for Bitfinex.

For some reason it triggered tons of requests for Bitfinex and screwed my rate limit.

Those are some expectations / suggestions

• If i send 3H or 3h the library should be able to "translate" it to the right format, TLDR: allow users to use lowercase or uppercase for the letters perhaps looking at this issue could help standardize it
• The library to normalise the timeframes, for instance 3h has lowercase h but 1D has uppercase D
• If the library can't determine the timeframe, don't do a request with undefined on the URL ( see screenshot )

Currently Bitfinex won't allow us to fetch 4H candles directly form their API.

It would be great to add this option and have tvcd consolidate the last 4x1H candles into 1x4H candles by calculating the highest high, lowest low, open, close, and summed volume of those candles.

Snyk is reporting a vulnerability on request package.

I can see you have all types under this file called exchanges but some types could be moved into smaller files.

For instance types related to candles could be moved to types/candles.ts

Bitfinex tickers use the format INCH:UST when the base or quote token is longer than 3 characters. Need to check if this line is correct:

https://github.com/wnz99/tvcd/blob/master/src/exchanges/bitfinex/utils/removeTradingPair.js#L8