load markets to files

// @NO_AUTO_TRANSPILE
import ccxt from '../../js/ccxt.js';
import path from 'path';
import fs from 'fs';
const enableRateLimit = true, 
// exchange defaults
// ------------------------------------------------------------------------
// path to your folder, for example '/myproject/markets' or 'C:/myproject/markets'
options = { enableRateLimit }, 
// writes to current working directory if left empty
// ------------------------------------------------------------------------
// use a reasonable value for maxConcurrency to avoid network congestion
// a burst of requests in a short period of time will cause
// excessive competition for networking resources within the application
folder = '', maxConcurrency = 7;
async function main() {
    const allExchanges = ccxt.exchanges.map(id => {
        try {
            return new ccxt[id](options);
        }
        catch (e) {
            console.log('Failed to initialize', id, e.constructor.name);
        }
    }).filter(x => x), allExchangesByIds = ccxt.indexBy(allExchanges, 'id'), exchangeIds = Object.keys(allExchangesByIds);
    const load = async () => {
        while (exchangeIds.length > 0) {
            const id = exchangeIds.pop();
            const exchange = allExchangesByIds[id];
            const file = path.join(folder, `saved-markets-${exchange.id}.json`);
            try {
                await exchange.loadMarkets();
                const { id, markets } = exchange;
                await fs.promises.writeFile(file, JSON.stringify({ id, markets }));
                console.log('Loaded markets from', id, 'to', file);
            }
            catch (e) {
                console.log('Failed to load markets from', id, 'to', file, e.constructor.name);
            }
        }
    };
    const started = ccxt.milliseconds();
    const loaders = Array(maxConcurrency).fill().map(x => load());
    await Promise.all(loaders);
    const stopped = ccxt.milliseconds();
    console.log('Done loading', allExchanges.length, 'exchanges in', ((stopped - started) / 1000).toFixed(2), 'seconds');
    // other code...
}
main();