Shared Load Markets

import ccxt from '../../js/ccxt.js';

// ----------------------------------------------------------------------------
// an example of how to load markets for each exchange just once
// in order to save memory and time for initializing multiple exchange instances
// see https://github.com/ccxt/ccxt/issues/7312 for details
// ----------------------------------------------------------------------------

const globalIds = [ 'binance', 'poloniex', 'bittrex', 'bitstamp' ]
const globalExchanges = {}

async function loadExchange (id) {
   try {
       const exchange = new ccxt[id] ()
       await exchange.loadMarkets ()
       globalExchanges[id] = exchange
   } catch (e) {
       // throw e // uncomment to break the entire program on any error
       // console.log (e) // print the exception and ignore this exchange
   }
}

async function main () {

   // initialize unique global exchange instances first
   await Promise.all (globalIds.map (async (id) => loadExchange (id)))
   console.log ('Loaded global exchanges:', Object.keys (globalExchanges))

   // load user exchanges and keys from a database or configure these via JSON
   const users = {
       'user1': {
           'binance': { 'apiKey': 'USER1_BINANCE_API_KEY', 'secret': 'USER1_BINANCE_SECRET' },
           'poloniex': { 'apiKey': 'USER1_POLONIEX_API_KEY', 'secret': 'USER1_POLONIEX_SECRET' }
       },
       'user2': {
           'poloniex': { 'apiKey': 'USER2_POLONIEX_API_KEY', 'secret': 'USER2_POLONIEX_SECRET' },
           'bittrex': { 'apiKey': 'USER2_BITTREX_API_KEY', 'secret': 'USER2_BITTREX_SECRET' }
       },
       'user3': {
           'bittrex': { 'apiKey': 'USER3_BITTREX_API_KEY', 'secret': 'USER3_BITTREX_SECRET' },
           'bitstamp': { 'apiKey': 'USER3_BITSTAMP_API_KEY', 'secret': 'USER3_BITSTAMP_SECRET' }
       }
   }

   // initialize local exchanges per user
   const localExchanges = {}
   for (const userId in users) {
       const userExchanges = {}
       for (const exchangeId in users[userId]) {
           if (exchangeId in globalExchanges) {
               const globalExchange = globalExchanges[exchangeId]
               const exchange = new ccxt[exchangeId] ({
                   // 'verbose': true, // uncomment for debug output
                   ... users[userId][exchangeId],
               });
               [
                   'ids',
                   'markets',
                   'markets_by_id',
                   'currencies',
                   'currencies_by_id',
                   'baseCurrencies',
                   'quoteCurrencies',
                   'symbols',
               ].forEach ((propertyName) => {
                   exchange[propertyName] = globalExchange[propertyName]
               })
               userExchanges[exchangeId] = exchange
           }
       }
       localExchanges[userId] = userExchanges
   }

   // print the loaded exchanges per user
   for (const userId in localExchanges) {
       console.log ('Loaded', userId, Object.keys (localExchanges[userId]))
   }
}

main ()