trycatch

An asynchronous try catch / exception handler with long stack traces for node.js

Background

See the "Background" from the long-stack-traces module.

Install

npm install trycatch

Basic Example

trycatch(function() {
	function f() {
		throw new Error('foo');
	}

	setTimeout(f, Math.random()*1000);
	setTimeout(f, Math.random()*1000);
}, function(err) {
	console.log("This is an asynchronous scoped error handler!\n", err.stack);
});

Output

$ node examples/setTimeout.js
This is an asynchronous scoped error handler!
 Error: foo
    at Object.f (/path/to/trycatch/examples/setTimeout.js:5:9)
    at Timer.callback (timers.js:83:39)
----------------------------------------
    at setTimeout
    at /path/to/trycatch/examples/setTimeout.js:8:2
    at Object.<anonymous> (/path/to/trycatch/examples/setTimeout.js:3:1)
    at Module._compile (module.js:404:26)
    at Object..js (module.js:410:10)
    at Module.load (module.js:336:31)
This is an asynchronous scoped error handler!
 Error: foo
    at Object.f (/path/to/trycatch/examples/setTimeout.js:5:9)
    at Timer.callback (timers.js:83:39)
----------------------------------------
    at setTimeout
    at /path/to/trycatch/examples/setTimeout.js:9:2
    at Object.<anonymous> (/path/to/trycatch/examples/setTimeout.js:3:1)
    at Module._compile (module.js:404:26)
    at Object..js (module.js:410:10)
    at Module.load (module.js:336:31)

Returning 500s on Server Request

http.createServer(function(req, res) {
	trycatch(function() {
		setTimeout(function() {
			throw new Error('Baloney!');
		}, 1000);
	}, function(err) {
		res.writeHead(500);
		res.end(err.stack);
	});
}).listen(8000);

Visit http://localhost:8000 and get your 500.

Nested trycatch

http.createServer(function(req, res) {
	trycatch(function() {
		process_request(req, res);
	}, function(err) {
		res.writeHead(500);
		res.end(err.stack);
	});
}).listen(8000);

function process_request(req, res) {
	// open db connection
	open_some_db();

	trycatch(function() {
		setTimeout(function() {
			throw new Error('whoopsy');
		}, 100);
	}, function(err) {
		// close the db connection
		close_some_db();

		// bubble the error
		throw err;
	});
}

This will allow your function to close the db before your 500 error.