Prettified error handling for Node.js

Installing

npm install prettified

Pretty printing exceptions

This sample code:

var errors = require('prettified').errors;
try {
	throw new Error("Example error");
} catch(err) {
	errors.print(err);
}

...will print errors using console.error() like this:

/---------------------------------- Error -----------------------------------\
| Error: Example error
+---------------------------------- stack -----------------------------------+
|     at Object.<anonymous> (/home/jhh/git/node-prettified/examples/format.js:3:8)
|     at Module._compile (module.js:449:26)
|     at Object.Module._extensions..js (module.js:467:10)
|     at Module.load (module.js:356:32)
|     at Function.Module._load (module.js:312:12)
|     at Module.runMain (module.js:492:10)
|     at process.startup.processNextTick.process._tickCallback (node.js:244:9)
\----------------------------------------------------------------------------/

Catch errors inside callbacks

The errors.catchfail([opts, ]callback) is a wrapper builder to catch exceptions inside function call.

It returns a function which when invoked calls the callback and passes all original arguments and returns the value untouched.

If exceptions are thrown it will catch them and print them using console.error() or by using a handler specified in opts. Handlers can be functions or Promise A defers (see the q library).

Example 1

You can simply wrap your existing callback handlers with catchfail like this:

require('fs').exists('test.txt', errors.catchfail(function(exists) {
	console.log('test.txt ' + (exists ? 'exists' : 'not found') );
}));

Example 2 -- with an error handler

If you like to handle the error you can pass an error handler as a first argument:

function do_error(err) {
	errors.print(err);
}
setTimeout(errors.catchfail(do_error, function() {
	throw new TypeError("Example error");
}), 200);

Example 3 -- with defers as an error handler

You can also use defers from the q library as an error handler:

function test() {
	var defer = require('q').defer();
	setTimeout(errors.catchfail(defer, function() {
		throw new TypeError("Example error");
	}), 200);
	return defer.promise;
}

test().fail(function(err) {
	errors.print(err);
});

Setting default error type

You can set default error type for uncatched errors like this:

errors.setDefaultError(MySystemError);