To be honest, I'm pretty new to coding and I managed to get this code which is running fine but I have no idea how to implement the options I mentionned above...     
var SteamCommunity = require('steamcommunity'); 
var SteamTotp = require("steam-totp"); 
var steam = new SteamCommunity(); 
var TradeOfferManager = require('steam-tradeoffer-manager'); 
var manager = new TradeOfferManager({ 
  domain: 'charredgrass.github.io', //for api key uses 
  language: 'en', 
  pollInterval: 30000 
});   
var logOnOptions = { 
accountName: '*****', 
password: '*****', 
twoFactorCode: SteamTotp.generateAuthCode('*****')  
};   
var identitySecret = '*****';   
//logs in via browser 
steam.login(logOnOptions, function(err, sessionID, cookies, steamguard) { 
if (err) { 
console.log('There was an error logging in! Error details: ' + err.message); 
process.exit(1); //terminates program 
} else { 
console.log('Successfully logged in as ' + logOnOptions.accountName); 
steam.chatLogon(); 
manager.setCookies(cookies, function(err) { 
if (err) { 
console.log(err); 
process.exit(1); 
} 
}); 
} 
steam.startConfirmationChecker(10000, identitySecret);  
});   
manager.on('newOffer', processTrade);   
function processTrade(offer) { 
console.log('New trade from ' + offer.partner); 
offer.accept(function(err) { 
if (offer.itemsToGive.length == 0 && offer.itemsToReceive.length > 0) { 
    offer.accept() } 
if (err) { 
console.log('Error accepting offer: ' + err.message); 
} else { 
console.log('Successfully accepted an offer.'); 
} 
}) 
}