Stateful x Stateless Components
Just as Stateful and Stateless web services, React components can also hold and manipulate state during application usage (Stateful) — or just be a simple component that takes the input props and returns what to display (Stateless).
A simple Stateless button component that depends on props only:
And a Stateful counter component example (using
As you can see, the last one’s constructor holds a component state, while the first one is a simple component that renders a text via props. This separation of concerns may look simple but makes
Button component highly reusable.
Container x Presentational Components
When working with external data, we can divide components into this two new categories.
Containers are responsible to reach data that lives outside React scope, like connecting to Redux or Relay — while
Presentational components are free of dependencies from the rest of the app, depending only on its own state or props received. Let’s take a users list as a
Presentational component example:
This list can be updated using our
This approach divides data-fetching from rendering and also makes
Let’s say you need to build an expandable menu component that shows some children content when user clicks on it. So, instead of controlling the state on its parent component, you can simply create a generic HOC to handle it:
This approach allows us to apply our logic to our
Now we can pass any children to
Another great way to make a component logic reusable is by turning your component children into a function — that’s why Render Callbacks are also called Function as Child Components. We can take an example of our expandable menu HOC and rewrite it using the Render Callback pattern:
Now we can pass a function as our
Toggleable component children:
The code above is already using a function as children, but, if we want to reuse it just as we did in our HOC example (multiple menus), we could simply create a new component that uses
Our brand new
ToggleableMenu component is ready to be used:
Menu component looks exactly the same as our HOC example!
This approach is really useful when we want to change the rendered content itself regardless of state manipulation: as you can see, we’ve moved our render logic to our
ToggleableMenu children function, but kept the state logic to our
This post is written by Gustavo Matheus.