One of the really great aspects of ExtJS 4 is the ability to configure how dependencies in your application are loaded, using asynchronous loading, synchronous loading, or a combination of both. This flexibility lets you really dig into detail when debugging, and you are able to file-by-file see where errors are occurring, where processes can be improved, etc. But even more, you can specify very granularly which files you want–and need–while excluding those you don’t.

Of course, all of this is really meant for your development environment. While it’s fine to load 70+ individual JavaScript files while working out your app’s functionality, you *definitely* do not want to impose such a monstrous load on your site’s actual visitors. This, after all, is why everyone uses ext-all.js. It’s the whole framework, smashed down into a single, minified file. But the problem is that it’s still the *whole* thing. There are probably a bunch of bits of ExtJS that you don’t need. This is where the Sencha SDK tool’ can help create a custom build that includes everything you need for your application to run, without the overhead of all the stuff you don’t.

In what follows, I’m going to outline my first ExtJS 4 build using the SDK More >