Using promises - Logging stack trace in fail handler

Question

I am rather new to nodejs so I will explain in a bit more detail what I am trying to do.

I have a webserver. If a request fails I want to log the stack trace of that exception, but deliver a error page and not crash the server.

As an example, the function handling the requests:

var Q = require('q');  var requestHandler = function () {     // Here I get the data etc. that was requested. As this is not important, just a dummy here     Q.resolve()         // Now I answer the request         .then(function (data) {             // Dummy Code representing the sending of a response             console.log('sending response …');             console.log('oh no! an exception');             // Now an Exception occurs             throw new Error('You did something wrong!');         })         // If there was any error, show the error page instead         .fail(function (err) {             // Dummy Code representing the sending of the error page             console.log('sending error page');             // Additionally I want to write the error into a log file             console.error('You had an error: ', err);         })         // If there was an error in the .fail-handler, I deserve the server to crash         .done(); };  // A request comes in, I want to call my handler requestHandler(); 

The console's output:

sending response … oh no! an exception sending error page You had an error:  [Error: You did something wrong!] 

I can't see a way to access the stack trace. But when I throw an exception in the .fail-handler (or just omit the complete .fail-handler), I get a stack trace on the console (but I'd have to restart the server).

So I guess my question is:

How do I access the stack trace in a promise fail handler?

EDIT: Any tips on how to improve the explanation are welcome, of course. If I didn't make myself clear, please let me know.

Answer 1

Logging the error object won't print error's stack trace. You need to ask for it specifically:

console.error('You had an error: ', err.stack);