Error code

[GHOST]

How can I get the error code when I send offer?

[Lesu]

Callbacks should have an "err" parameter when they may return errors. "TradeOffer.send" does indeed let you catch errors, if that's the function you're talking about, by doing something like:

offer.send(function(err) {
    console.log(err);
});

[GHOST]

I know this, but I want to get error code, not error message. 

[Dr. McKay]

err.eresult, provided it's available.