Component maturity model

ui coponents illustration

Think you are a programmer, a front-end programmer. You collaborate with the development of a web product. Your workmates are back-end programmers, designers and product owners. So, in an ordinary day, in a casual meeting, in a simple presentation or in a regular chat among team members, you make use of a word, a very simple word. Component.

You could be sharing something you learnt on your latest reading, making a suggestion about the way of developing user interfaces or making just a joke. Regardless you were doing, at the exact moment you finished to pronounce the last syllable of this so simple word called component, something very complex is gonna start to happen.

Your designer will invoke the powers of Design System god, blessed with the glory of Atomic Design and baptized with each variable containing on his set of Design Tokens. Your product owner, bewitched by the reusability magic - and suffocated by the Gantt chart that demands him to ship dozens of new features - will ask you a thousand times: So does it allow us to deliver more features in less time?. And, finally, the back-end programmer will say nothing more than: I already used Bootstrap once. I hate CSS.

Even though it has four syllables only, the word component causes zillions of different interpretations and expectations. So easy to say it, so hard to define it.

At this moment, you might be convinced that I’m gonna introduce a definition for the word component that will cause you a mindquake. The definition that, once pronounced, is able to incinerate any ambiguity.

No man, I’m sorry. Unfortunately, I didn’t find that one and only powerful definition, but I’ll try to help you offering three! They represent what I called Component Maturity Model.

Level Zero: Chaos

Welcome to the chaos. At this level, anyone of that zillions of different interpretations doesn’t even exist. Everything is reduced to blood, sweat and tears. Nothing can be reused and any change is very expensive.


  • No predefined HTML structure that can be replicated.
  • No predefined CSS classes that could be used together those predefined HTML structures.
  • Markup, styles and logic are not encapsulated.

Side Effects

  • Unnecessary CSS. With no predefined CSS classes, already existing styles are redundantly written as new classes. Within a short period of time, you end up with different classes in different stylesheets doing the exact same thing.
  • Unnecessary scripts. Since the existing logic is not encapsulated, the same behaviour is replicated along the system.
  • Zero reuse. With no predefined HTML structures, those different CSS Classes multiply themselves at the same speed which new random HTML structures are created.
  • Very expensive changes. With the same responsibility replicated in several other parts of the application, even the smallest change could become the worst nightmare since you don’t have any idea of how many parts of the system need to be changed.
<div class="finance-btn-attach-file glyphicons paperclip">
  <i></i>Attach documents

A generic button to upload files got coupled to a stylesheet already connected to a business domain (finance). Markup and logic are not encapsulated and will be replicated with other classes and markup on every part of the system which a file upload button be necessary again.

Level One: CSS Components

Stage which predefined HTML structures are available and CSS classes can be reused.


  • Predefined HTML structures.
  • Predefined CSS classes.
  • Markup, styles and logic still not encapsulated.

Side Effects

  • Less CSS. With predefined HTML structures, CSS classes can be reused from now on. New CSS classes are drastically avoided and much less CSS needs to be written.
  • Unnecessary markup. Although you already have predefined HTML structures, they aren’t encapsulated. That said, unnecessary markup still continues to be replicated along the system.
  • Unnecessary scripts. Same as markup, the lack of encapsulation still makes the behaviour to be replicated in different parts of the system.
  • Expensive changes At least on CSS, changes become less expensive. However, any change related to the markup or the behaviour still costs a lot.
<button class="btn btn-primary">
  <i class="glyphicons glyphicons-download-alt"></i>Download

This is a predefined HTML structure for a button styled as primary and containing an icon at the left of its text. Every part of the system that requires a button like this are now able to achieve the same result replicating that HTML structure with those CSS classes.

Level Two: Custom Elements

Welcome productivity! This is the stage which everything, absolutely everything, is encapsulated in its own component.


  • Predefined HTML structures.
  • Predefined CSS classes.
  • Markup, style and logic are encapsulated.

Side Effects

  • Each component becomes the single authority about one only system's responsibility.
  • Everything becomes reusable.
  • Changes are cheap.
<my-button data-theme="primary" data-icon-name="paperclip">
  Attach Documents

The custom element above (my-button) is the single part of the system where anything related to all application buttons is handled.

As you can see, that one and only powerful definition I really can’t offer at this time, but I hope these three levels of maturity may help you to explain to your workmates what kind of components are you talking about, what level of maturity you expected to have and which level you would like to reach.