[node.js] How to specify HTTP error code?

I have tried:

app.get('/', function(req, res, next) {
    var e = new Error('error message');
    e.status = 400;
    next(e);
});

and:

app.get('/', function(req, res, next) {
    res.statusCode = 400;
    var e = new Error('error message');
    next(e);
});

but always an error code of 500 is announced.

I would recommend handling the sending of http error codes by using the Boom package.

A simple one liner;

res.status(404).send("Oh uh, something went wrong");

I tried

res.status(400);
res.send('message');

..but it was giving me error:

(node:208) UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent.

This work for me

res.status(400).send(yourMessage);

Old question, but still coming up on Google. In the current version of Express (3.4.0), you can alter res.statusCode before calling next(err):

res.statusCode = 404;
next(new Error('File not found'));

You can use res.send('OMG :(', 404); just res.send(404);

Express deprecated res.send(body, status).

Use res.status(status).send(body) instead

The version of the errorHandler middleware bundled with some (perhaps older?) versions of express seems to have the status code hardcoded. The version documented here: http://www.senchalabs.org/connect/errorHandler.html on the other hand lets you do what you are trying to do. So, perhaps trying upgrading to the latest version of express/connect.

I'd like to centralize the creation of the error response in this way:

app.get('/test', function(req, res){
  throw {status: 500, message: 'detailed message'};
});

app.use(function (err, req, res, next) {
  res.status(err.status || 500).json({status: err.status, message: err.message})
});

So I have always the same error output format.

PS: of course you could create an object to extend the standard error like this:

const AppError = require('./lib/app-error');
app.get('/test', function(req, res){
  throw new AppError('Detail Message', 500)
});

'use strict';

module.exports = function AppError(message, httpStatus) {
  Error.captureStackTrace(this, this.constructor);
  this.name = this.constructor.name;
  this.message = message;
  this.status = httpStatus;
};

require('util').inherits(module.exports, Error);

From what I saw in Express 4.0 this works for me. This is example of authentication required middleware.

function apiDemandLoggedIn(req, res, next) {

    // if user is authenticated in the session, carry on
    console.log('isAuth', req.isAuthenticated(), req.user);
    if (req.isAuthenticated())
        return next();

    // If not return 401 response which means unauthroized.
    var err = new Error();
    err.status = 401;
    next(err);
}

In express 4.0 they got it right :)

res.sendStatus(statusCode)
// Sets the response HTTP status code to statusCode and send its string representation as the response body.

res.sendStatus(200); // equivalent to res.status(200).send('OK')
res.sendStatus(403); // equivalent to res.status(403).send('Forbidden')
res.sendStatus(404); // equivalent to res.status(404).send('Not Found')
res.sendStatus(500); // equivalent to res.status(500).send('Internal Server Error')

//If an unsupported status code is specified, the HTTP status is still set to statusCode and the string version of the code is sent as the response body.

res.sendStatus(2000); // equivalent to res.status(2000).send('2000')