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януари 27, 2013

Decoupling components for frontend development.

Introduction: It appears the era of monolithic UI libraries is coming to an end.

It has been irritating for years: you go deep into a project for months just to realize that you need a certain type of UI component that is not available for your set of libraries but is readily available for another (for example it is written for Mootools, but you use jQuery or it is in Dojo but you are actually using jQuery).

So before you even start you have to have in mind all the components you might need. Then o and hunt for a library that has them all or at least most of them. You then have to spend time and learn their component idioms (i.e. how a new component is created or composed from existing ones). This is one of the hardest things to grasp in a new library in addition to its build model.

Build model is another opinion in a library that you can't (or can but hardly) change. Some libraries (smaller ones) do not provide a build model and you are on your own, however if a build model is selected you have to stick to it. If the library uses AMD you have to stick to AMD. If the library uses CommonJS you ave to stick to browserify or a similar one. The primary goal being dependency management, it often includes concatenation and minification steps.

The problem often overseen is that you can achieve greater responsiveness if you separate initialization code from the rest of your application. RequireJS supports building your application with build units allowing such set ups. Closure compiler also allows you to separate your code into loadable modules. However with browserify you are on your own. You have to manage the dependencies and the build step if you elect to use one.

A new concept recently introduced by TJHolowwaychuck is components: The idea is that you could develop a reusable component and put it in its own repository on github or on a private git service and then reuse it from within another component or in an application. The components could contain css, JavaScript and HTML.

I find the idea great, however the execution and the design are not so great. The following problems stick out pretty fast:
  • while component management is made easy with this project, you are required to use only one final file in your application, so modularization and modular loading is not possible yet.
  • while the builder used in the project provides a hooking mechanism it is unusable unless you wither alter the builder itself locally to attach your own hooks (i.e. ones that are not provided by default) or you have to fork the component npm package to make it require augmented builder package where you have extended the base builder. This makes the project really hard to augment in transparent manner and locks you into constant chasing with the original. 
On the other hand the naming convention used and the plumbing added to make ti work makes the project a real pearl in the dust: no more strange and ugly names (as in the author's example you could use 'tip' for your project name, no more tippie, tipsy, tips, tiping etc) thanks to the repo/project naming convention. The names are disambiguated automatically and this works great.

The even greater thing about this is that dependencies are managed automatically for you and transparently and that you can concentrate on a smaller, testable units of code. This IMO encourages decoupling (similar to AMD) but removes the extra complexity of AMD (the paths for example could be a real hell if you try to mix several repositories). Fattening out the directory tree was a great win for this project. 

Conclusion: One thing we should get used to in the coming months and years is that monolithic application model (an application that consists of only one pre-build file) is going away. Shadow DOM, Web components, JavaScript modules etc are making steps forward and the sooner we understand the speed and memory implications of those the better we can implement them in your projects. Until now - use decoupled code as much as possible.

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