I tried this, it worked and logged in but then gave me the following error. EDIT: Nevermind, I was using the wrong value for my identity_secret. I changed it and it worked
var timeOffset;
//getting offset for log in
SteamTotp.getTimeOffset(function(error, offset, latentcy){
timeOffset=offset;
});
client.logOn({
accountName: Config.username,
password: Config.password,
twoFactorCode: SteamTotp.getAuthCode(Config.shared_secret, timeOffset)
});