Model-View-Controller, or MVC for short, is an software architecture pattern for user interfaces that creates a distinction between the display (or view), the data (or model), and the interaction (or controller). In this article, I’m going to focus specifically on how MVC applies to the client side of web applications. What I mean is that MVC in a web based ui translates to

• HTML as the model
• CSS as the view
• Javascript as the controller

This separation of concerns means that as long as the model stays consistent, you can

1. Create multiple views for the same model
2. Develop the controller and views independently

For a great example of 1 checkout css Zen Garden. Here, the same HTML (the model) can be seen with many different views.

Now checkout the jquery ui demos for a clear example of both 1 and 2. Again, the same HTML has many different views with the various CSS themes, and you can also see jquery ui controller code in action. The Javascript manipulates the model, affecting what you see and how you see it, independently of which theme (or view) you choose.

What this all means is that you can create semantically correct HTML optimized for search engines, CSS so your page looks good for humans, and Javascript to make your page interactive. In other words, content can be separated from presentation, which can be separated from the interaction behavior. The CSS and Javascript can be developed (mostly) independently and only be loosely coupled to the HTML.

Taking this a step further, it’s possible to create generic views and controllers using CSS and Javascript that work on a small generic model. jquery ThickBox is an example of this, since it can be used on any page where you have <a class='thickbox' ...>...</a>. As long as your HTML supports the generic model, you can reuse the CSS and Javascript across multiple pages.