NodeJS/Express app.use sequence and usage

Question

I tried to separate my node routing into two parts: HTML/App and REST. Here is what I've done:

app.js:

var appPort = process.env.PORT || 80;
var express = require('express');
var http = require('http');
var appRouter = require('./routes/index');
var restRouter = require('./routes/rest');
var app = express();
var srv = http.createServer(app);

app.set('port', appPort);
app.set('view engine', 'jade');
app.use(express.static(path.join(__dirname, 'public')));

app.use('/api/rest/', restRouter); // this seems not working .. I never get the expected response
app.use('/', appRouter);           // I get this even with localhost/api/rest/...

var server = srv.listen(app.get('port'), function() {
    debug('Express server listening  ' + server.address().address + ':' + server.address().port);
});

index.js:

var express = require('express');
var router = express.Router();

router.get('/*', function (req, res) {
    res.send('HOME')
});

module.exports = router;

rest.js

var express = require('express');
var router = express.Router();

router.get('/api/rest/*', function(req, res) {
    res.send('REST API');
});

module.exports = router;

My questions:
1. It's possible in general to build multiple routers in this way?
2. Does the sequence of get.use matter, and/or do I have to deal with 'next'?
3. In case I would like to access a database inside the router can I hand over a parameter like this:

// ...
var client  = new pg.Client(dbConnection);
// ...
app.use('/', appRouter(client));

Answer 1

1) It is possible to build multiple routers this way.

Because you are using this:

app.use('/api/rest/', restRouter);

your route calls in rest.js will be relative to /api/rest/ which means your code should be modified in rest.js to look like this:

router.get('*', function(req, res) {
    res.send('REST API');
});

I would also encourage you to see the Express multi-router example on GitHub. It illustrates this point very clearly by showing a REST app with versioned routes.

2) The order of things matter

See the Express documentation for app.use and you will note:

Middleware functions are executed sequentially, therefore the order of middleware inclusion is important.

If you reverse the order of your app.use calls, the router.get('/*', function (req, res) { line in index.js will catch everything before you get to other routes...defeating your purpose.

Also, if you don't call next, Express has no way to know that you are done or even that you want to continue to the next middleware or route.

3) The database question is a modules/scope question

This is more of a scope question than an Express question. I'd suggest looking up some of the excellent writing about javascript scope and also on how Node handles modules.