Semantic Web Component Design: Radios, dropdowns, and tabs are the same thing
Early on in the rewrite of Appuri's portal that we started on after having a designer and development team from the MVP, and in our transition from Angular to Knockout, I was looking around at different widget / web component libraries and what I could leverage that would fit the designer's use cases and style, as well as a clean design.
One thing that always drove me nuts about our previous UI was a mismash of different components doing the same thing. We had ui-select2, ui-select from the Angular UI team, angular-multi-select for some multiselect cases, and a custom directive for radio-like toggle boxes.
Each control offered some little feature that another didn't (except
ui-select2 which was just in code we didn't get around to refactoring yet). Why is this? All of them are trying to do the same thing on a higher semantic level: The user needs to pick an one (or more) options from this fixed set of options. How that looks is a styling concern.
- Model: Your data as an object
- Controller/ViewModel/Presenter/Whatever: the business logic of your app
View: The HTML templates for your app
But after using a few (Knockout, Angular, Ember, and Backbone) I've noticed there's a forth component. It's the widgety type of logic - logic that isn't about your business, but extents the browser functionality - that cool datepicker, color picker, an awesome visualization with D3, maybe a 3D flip switch intstead of a checkbox. That stuff that is a DMZ to the DOM - Knockout's
bindingHandlers, Angular's directives, and Handlebar helpers. They aren't about how you map your view model / controller to the DOM, but about extending the functionality of the DOM.
Why is this important? Keeping selector strings out of your controllers and view models is vital for the separation of concerns and tesability. Keeping this 4th aspect as the DMZ to the DOM helps to separate these concerns. Say you do have a complicated problem to solve in your app, and you come up with a cool way to visuallize it. You could put it all in one module... but now what happens when you release it and users don't like that widget and they want something more traditional? It will be harder to pull it out. Or the opposite where that widget is really awesome and you want to use it elsewhere... now lots of work to pull the business logic out. Let those two evolve independently and they grow and improve much more rapidly.