Rendering Children in React
There are a number of different ways to render child elements in React, and when it comes to component design, some solutions are more flexible than others. Let’s look at a few options.
Array or object prop
object prop to render child elements is the least flexible option because the component itself controls the type of children that are rendered and their props. This approach might be suitable for components that prioritize consistency over flexibility because the component controls all aspects of rendering.
Here the component is saying: Just give me the data — I’ll take care of rendering the children.
In this example, the consumer provides an array of items and the
Tabs component decides what to render. This makes it difficult for the consumer to override the appearance and behavior of the tabs.
Flexibility: 🧘♂️ 🧘♂️
children prop to compose child elements is idiomatic in React. This approach is a bit more flexible because it allows the consumer to decide how to render the children. However, the result is a tight coupling between the component and its children. For the component to control its children, they must expose the necessary props.
Here the component is saying: Give me the children and I’ll slot them in somewhere. Just make sure they expose the required props so I can set them.
In this example, the consumer wants to use
FancyTab components instead of
Tab components. This works because
FancyTab exposes the required props
Flexibility: 🧘♂️ 🧘♂️ 🧘♂️
Using a render prop to compose child elements is an advanced pattern that delegates all aspects of rendering to the consumer. Furthermore, it results in a loose coupling between the component and its children, allowing the consumer to render children with an otherwise incompatible API.
Here the component is saying: Render the children when I call this function. I’ll expose an API to help you integrate your super-custom child components.
In this example, the consumer wants to use custom
HoverTab components, but there’s one problem: The
HoverTab component exposes an
onMouseEnter prop instead of
onClick and an
active prop instead of
selected. The consumer needs a way to adapt one API to another. This is where render props come in handy.
Tabs component is rendering, it invokes the
children prop (now a function) and passes it
setSelectedIndex. This allows the consumer to map the
HoverTab props to the API provided by the
See also: Inversion of Control
Which approach is best?
It depends whether your component prioritizes consistency or flexibility. If you want to lock-down the design and behaviour of your component then an
array prop might be best. If you want to provide the consumer with ultimate flexibility, then go for a render prop.
13 Jul 2019
- Event Sourcing: Read Models are Overrated
29 Jun 2019
- Rendering Children in React
06 Feb 2019
- Hacking Image Interpolation for Fun and Profit
13 Jan 2019
- The Perils of Jest Snapshot Testing
07 Jan 2019
- A Better Way to Test Your React-Redux App
01 Jan 2019
- Firebase + Create React App
01 Aug 2018
- Partial Application in Action
29 Sep 2017
- Invalidate Pattern
24 Aug 2017
- Using SVG to Shrink Your PNGs
07 Sep 2014
- Adaptive Content
06 Feb 2013