Gateio Open Close Contract

// @NO_AUTO_TRANSPILE
import ccxt from '../../js/ccxt.js';
const exchange = new ccxt.gate({
    'apiKey': 'YOUR_API_KEY',
    'secret': 'YOUR_SECRET',
    'options': {
        'defaultType': 'swap',
        'marginMode': 'cross'
    },
});
(async () => {
    // exchange.setSandboxMode (true)
    const markets = await exchange.loadMarkets();
    // exchange.verbose = true // uncomment for debugging purposes if necessary
    // Example: creating and closing a contract
    let symbol = 'LTC/USDT:USDT';
    let type = 'market';
    let side = 'buy';
    let amount = 1;
    let price = undefined;
    try {
        // fetching current balance
        const balance = await exchange.fetchBalance();
        console.log(balance);
        // placing an order / opening contract position
        const order = await exchange.createOrder(symbol, type, side, amount, price);
        console.log(order);
        // closing it by issuing an oposite contract 
        // and therefore close our previous position
        side = 'sell';
        type = 'market';
        const reduce_only = true;
        const params = { 'reduce_only': reduce_only };
        const opositeOrder = await exchange.createOrder(symbol, type, side, amount, price, params);
        console.log(opositeOrder);
    }
    catch (e) {
        console.log(e.constructor.name, e.message);
    }
})();