Fetch All Tickers To Files

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

const { noLocate } = ololog;
const log = noLocate;

import fs from 'fs';

// the numWorkers constant defines the number of concurrent workers
// those aren't really threads in terms of the async environment
// set this to the number of cores in your CPU * 2
// or play with this number to find a setting that works best for you

const numWorkers = 8;(async () => {

   // make an array of all exchanges
   const exchanges = ccxt.exchanges

       // filter coinmarketcap and theocean
       // coinmarketcap isn't really an exchange
       // theocean requires web3 dependencies to be installed

       .filter (id => ![ 'coinmarketcap', 'theocean' ].includes (id))

       // instantiate each exchange and save it to the exchanges list

       .map (id => new ccxt[id] ())

   // the worker function for each "async thread"
   const worker = async function () {

       // while the array of all exchanges is not empty
       while (exchanges.length > 0) {

           // pop one exchange from the array
           const exchange = exchanges.pop ()

           // check if it has the necessary method implemented
           if (exchange.has['fetchTickers']) {

               // try to do "the work" and handle errors if any
               try {

                   // fetch the response for all tickers from the exchange
                   const tickers = await exchange.fetchTickers ()

                   // make a filename from exchange id
                   const filename = exchange.id + '.json'

                   // save the response to a file
                   fs.writeFileSync (filename, JSON.stringify ({ tickers }));

                   // print out a message on success
                   log.green (exchange.id, 'tickers saved to', filename)

               } catch (e) {

                   // in case of error - print it out and ignore it further
                   log.red (e.constructor.name, e.message)
               }

           } else {

               log.red (exchange.id, "has['fetchTickers'] = false");
           }
       }
   }

   // create numWorkers "threads" (they aren't really threads)
   const workers = [ ... Array (numWorkers) ].map (_ => worker ())

   // wait for all of them to execute or fail
   await Promise.all (workers)

}) ()