How to catch http client request exceptions in node.js

http.createClient has been deprecated.

Here is a quick example of how to handle errors using the new http.request:

var http = require("http");var options = {    host : "www.example.com"};var request = http.request(options, function(req) {    ...});request.on('error', function(err) {    // Handle error});request.end();

I stumbled across another solution while I was researching a similar problem. http.Client emits an 'error' event if a connection can't be established for any reason. If you handle this event then the exception won't be thrown:

var http = require('http');var sys = require('sys');function checkSite(url) {    var site = http.createClient(80, url);    site.on('error', function(err) {        sys.debug('unable to connect to ' + url);    });    var request = site.request('GET', '/', {'host': url});    request.end();    request.on('response', function(res) {        sys.debug('status code: ' + res.statusCode);    });}checkSite("www.google.com");checkSite("foo.bar.blrfl.org");

Of course, the connection error and the response to the request both arrive asynchronously, meaning that simply returning the request won't work. Instead, you'd have to notify the caller of the results from within the event handlers.

Unfortunately, at the moment there's no way to catch these exceptions directly, since all the stuff happens asynchronously in the background.

All you can do is to catch the uncaughtException's on your own:

var http = require('http');function checkSite(url){    var site = http.createClient(800, url);    var request = site.request('GET', '/', {'host': url});    request.end();    return request;}process.on('uncaughtException', function (err) {    console.log(err);}); checkSite('http://127.0.0.1');

Which in this case (notice port 800) logs:

{ message: 'ECONNREFUSED, Connection refused',  stack: [Getter/Setter],  errno: 111,  syscall: 'connect' }

Node.js is still under heavy development and there sure will be a lot of progress in the next couple of months, right now focus seem to be on fixing performance bugs for 3.x and making the API somewhat stable, because after all Node.js is mainly a server so throughput matters.

You can file a bug though, but be warned crashes etc. have way higher priority than features, and most new features make it in via fork pull requests.

Also for the current Roadmap of Node.js watch this talk by Ryan Dahl (Node's Creator):
http://developer.yahoo.com/yui/theater/video.php?v=yuiconf2010-dahl