Call function of app.js from within module in node.js?

Question

Let's say I have the following app.js (obviously very simplified):

var express = require('express'),
    app = express.createServer();

// include routes
require('./lib/routes')(app);

// some random function
var foo = function() {
    return 'bar';
};

// another random function
var foo2 = function() {
    return 'bar2';
};

And then I have the routes module:

module.exports = function(app){
    app.get('/some/route', function(req, res){
        var fooBar = foo(),
            fooBar2 = foo2();

        res.end(fooBar + fooBar2);
    });
};

This obviously doesn't work since foo and foo2 weren't defined within the module. Is there a way to make this work, or at least a different pattern to better accomplish what this?

Answer 1

Well you can just put these two functions in an object and pass them on the initialization of the routes.js .

var express = require('express'),
    app = express.createServer();

// some random function
var foo = function() {
    return 'bar';
};

// another random function
var foo2 = function() {
    return 'bar2';
};

var fns = {foo : foo, foo2: foo2}

// include routes
require('./lib/routes')(app, fns);

in routes:

module.exports = function(app, fns){
    app.get('/some/route', function(req, res){
        var fooBar = fns.foo(),
            fooBar2 = fns.foo2();

        res.end(fooBar + fooBar2);
    });
};

This is how would I do it. You can also include them in the app object. Beside passing them in init functions, you can also export those two functions and require them in routes.js.

var express = require('express'),
    app = express.createServer();

// some random function
var foo = function() {
    return 'bar';
};

// another random function
var foo2 = function() {
    return 'bar2';
};

module.exports = {foo : foo, foo2: foo2}

// include routes
require('./lib/routes')(app, fns);

in routes:

module.exports = function(app){
    var fns = require('../app.js');
    app.get('/some/route', function(req, res){
        var fooBar = fns.foo(),
            fooBar2 = fns.foo2();

        res.end(fooBar + fooBar2);
    });
};

But I don't like the idea of it, since it makes circular dependencies. Don't have any good feelings about them.