Node.js module loading

Question

I am currently building a web app with Node and I am curious as to how Node loads its required files or modules.

I am using express for view and server config, however I am finding that all the Node examples (I know express offers an MVC example) don't really conform to the general MVC pattern. I am also aware that Node is not necessarily suited for MVC, but bear with me, because I like MVC.

If you consider the following route declaration, it would be effective to use this as a controller, since here you can control the request and response logic:

module.exports = function (app) {

app.get('/', function (req, res) {

    res.render('index', { layout: false });


});

To try and follow an MVC architecture I have effectively divided the routes up into its relevant paths in effect creating controllers. However whenever I have a different route file it must contain its own set of required modules. For example:

var mongo = require('mongoskin');

I would then declare the required route files in the app.js or server.js file that holds the server config settings.

I am wondering whether splitting up the routes like this would slow down the application since I am unaware of how Node loads its modules. If it is loading as per needed then surely this implementation must slow it down?

JohnnyHK · Accepted Answer · 2013-01-30 15:22:50Z

4

Required modules are only loaded once and then cached, so feel free the break up your app into as many modules as needed to cleanly organize your app. If you have 20 files that call require('mongoskin'), that module is still only loaded once.

answered Jan 30, 2013 at 15:22

JohnnyHK

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nimrodm · Accepted Answer · 2013-01-30 15:23:11Z

2

Quoting from the node.js documentation:

Modules are cached after the first time they are loaded. This means (among other things) that every call to require('foo') will get exactly the same object returned, if it would resolve to the same file.

Multiple calls to require('foo') may not cause the module code to be executed multiple times. This is an important feature. With it, "partially done" objects can be returned, thus allowing transitive dependencies to be loaded even when they would cause cycles.

answered Jan 30, 2013 at 15:23

nimrodm

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