– React lessons learned – React lessons learned Jun. 6th, 2018 Evan Willhite
Sales going up! – React lessons learned

June 6th, 2018

I recently had the privilege of helping launch a new React Frontend for their Drupal 7 project. Although I was fairly new to using React, I was able to lean on Four Kitchens’ senior JavaScript engineering team for guidance. I thought I might take the opportunity to share some things I learned along the way in terms of organization, code structuring and packages.


As a lead maintainer of Emulsify, I’m no stranger to component-driven development and building a user interface from minimal, modular components. However, building a library of React components provided me with some new insights worth mentioning.

Component Variations

If a component’s purpose starts to diverge, it may be a good time to split the variations in your component into separate components. A perfect example of this can be found in a button component. On any project of scale, you will likely have a multitude of buttons ranging from actual <button> elements to links or inputs. While these will likely share a number of qualities (e.g., styling), they may also vary not only in the markup they use but interactions as well. For instance, here is a simple button component with a couple of variations:

Even with the simplicity of this example, why not separate this into two separate components? You could even change this component to handle that fork:

React makes this separation so easy, it really is worth a few minutes to define components that are distinct in purpose. Also, testing against each one will become a lot easier as well.

Reuse Components

While the above might help with encapsulation, one of the main goals of component-driven development is reusability. When you build/test something well once, not only is it a waste of time and resources to build something nearly identical but you have also opened yourself to new and unnecessary points of failure. A good example from our project is creating a couple different types of toggles.  For accessible, standardized dropdowns, we introduced the well-supported, external library Downshift.:

In a separate part of the UI, we needed to build an accordion menu:

Initially, this struck me as two different UI elements, and so we built it as such. But in reality, this was an opportunity that I missed to reuse the well-built and tested Downshift library (and in fact, we have a ticket in the backlog to do that very thing). This is a simple example, but as the complexity of the component (or a project) increases, you can see where reusage would become critical.


And speaking of dropdowns, React components lend themselves to a great deal of flexibility. We knew the “drawer” part of the dropdown would need to contain anything from an individual item to a list of items to a form element. Because of this, it made sense to make the drawer contents as flexible as possible. By using the open-ended children prop, the dropdown container could simply just concern itself with container level styling and the toggling of the drawer. See below for a simplified version of the container code (using Downshift):

This means we can put anything we want inside of the container:

This kind of maximum flexibility with minimal code is definitely a win in situations like this.


The Right Component for the Job

Even though the React documentation spells it out, it is still easy to forget that sometimes you don’t need the whole React toolbox for a component. In fact, there’s more than simplicity at stake, writing stateless components may in some instances be more performant than stateful ones. Here’s an example of a hero component that doesn’t need state following AirBnB’s React/JSX styleguide:

When you actually need to use Class, there are some optimizations you can make to at least write cleaner (and less) code. Take this Header component example:

In this snippet, we can start by simplifying the React.Component extension:

Next, we can export the component in the same line so we don’t have to at the end:

Finally, if we make the toggleOpen() function into an arrow function, we don’t need the binding in the constructor. And because our constructor was really only necessary for the binding, we can now get rid of it completely!


React has some quick wins for catching bugs with built-in typechecking abilities using React.propTypes. When using a Class component, you can also move your propTypes inside the component as static propTypes. So, instead of:

You can instead have:

Also, if you want to limit the value or objects returned in a prop, you can use PropTypes.oneOf and PropTypes.oneOfType respectively (documentation).

And finally, another place to simplify code is that you can deconstruct the props option in the function parameter definition like so. Here’s a component before this has been done:

And here’s the same component after:


Finally, a word on packages. React’s popularity lends itself to a plethora of packages available. One of our senior JavaScript engineers passed on some sage advice to me that is worth mentioning here: every package you add to your project is another dependency to support. This doesn’t mean that you should never use packages, merely that it should be done judiciously, ideally with awareness of the package’s support, weight and dependencies. That said, here are a couple of packages (besides Downshift) that we found useful enough to include on this project:


If you find yourself doing a lot of classname manipulation in your components, the classnames utility is a package that helps with readability. Here’s an example before we applied the classnames utility:

With classnames you can make this much more readable by separating the logic:

React Intersection Observer (Lazy Loading)

IntersectionObserver is an API that provides a way for browsers to asynchronously detect changes of an element intersecting with the browser window. Support is gaining traction and a polyfill is available for fallback. This API could serve a number of purposes, not the least of which is the popular technique of lazy loading to defer loading of assets not visible to the user.  While we could have in theory written our own component using this API, we chose to use the React Intersection Observer package because it takes care of the bookkeeping and standardizes a React component that makes it simple to pass in options and detect events.


I hope passing on some of the knowledge I gained along the way is helpful for someone else. If nothing else, I learned that there are some great starting points out there in the community worth studying. The first is the excellent React documentation. Up to date and extensive, this documentation was my lifeline throughout the project. The next is Create React App, which is actually a great starting point for any size application and is also extremely well documented with best practices for a beginner to start writing code.