Building Decoupled Large-scale Applications Using JavaScript (And jQuery)

Building Decoupled Large-scale Applications Using JavaScript (And jQuery)

These are the slides for a talk I gave at jQuery Conf UK, where I explored a number of effective design patterns for scaling applications using JavaScript and jQuery. Unlike some of my previous talks on this subject, today I focused on the importance of decoupling.

"In computer science, coupling is the degree to which each module relies on a number of other modules. By decoupling your application, you're able to easily extend and develop one layer without affecting the other."

As a JavaScript developer (or a heavy jQuery user) it's important to remember that you can easily take advantage of patterns as simple as Pub/Sub (or a Mediator) for decoupling your application. In addition to helping solve the problem of tight coupling, patterns such as these can encourage separating your application logic into simpler, more independent modules that can be more easily reused. For anyone wishing to read up more about Pub/Sub, I wrote a detailed article on it for ScriptJunkie here:

You can also benefit from patterns that can be found in libraries like jQuery (such as the Facade) to implement all kinds of fun concepts like limited public APIs or application-level security. Later in the talk I show how a Mediator can also be used to gain greater control over modules, like being able to start, stop and restart them to enable building applications that can 'fix' breakages. This helps create a user-experience that is potentially a lot more robust than what we see in many applications today. My more detailed article on these topics can be found at

Note: Remember that the architecture presented is flexible and you're free to use as few or as many of the patterns covered in your applications.

For those looking for the demo application shown near the end of the talk, the source to it can be found here:

Links to articles I've written related to this talk can be found in the 'Further Reading' section.

A gist I posted with a few different ways to implement Pub/Sub with jQuery can be found at and I'm also happy to recommend the Pub/Sub solution in AppendTo's AmplifyJS ( Finally, simple Mediator pattern implementations can be found here:


Addy Osmani

February 10, 2012