How to redirect 404 errors to a page in ExpressJS?

Problem

I don’t know a function for doing this, does anyone know of one?

Problem courtesy of: Julio García

Solution

I found this example quite helpful:

So it is actually this part:

// "app.router" positions our routes
// above the middleware defined below,
// this means that Express will attempt
// to match & call routes _before_ continuing
// on, at which point we assume it's a 404 because
// no route has handled the request.

app.use(app.router);

// Since this is the last non-error-handling
// middleware use()d, we assume 404, as nothing else
// responded.

// $ curl http://localhost:3000/notfound
// $ curl http://localhost:3000/notfound -H "Accept: application/json"
// $ curl http://localhost:3000/notfound -H "Accept: text/plain"

app.use(function(req, res, next){
res.status(404);

// respond with html page
if (req.accepts('html')) {
res.render('404', { url: req.url });
return;
}

// respond with json
if (req.accepts('json')) {
res.send({ error: 'Not found' });
return;
}

// default to plain-text. send()
res.type('txt').send('Not found');
});

Solution courtesy of: Felix

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