In programming, composition allows you to build more complex functionality by combining small and focused functions.
For example, think about using map()
to create a new array from an initial set, and then filtering the result using filter()
:
const list = ['Apple', 'Orange', 'Egg']
list.map(item => item[0]).filter(item => item === 'A') //'A'
In React, composition allows you to have some pretty cool advantages.
You create small and lean components and use them to compose more functionality on top of them. How?
Create specialized version of a component
Use an outer component to expand and specialize a more generic component:
const Button = props => {
return <button>{props.text}</button>
}
const SubmitButton = () => {
return <Button text="Submit" />
}
const LoginButton = () => {
return <Button text="Login" />
}
Pass methods as props
A component can focus on tracking a click event, for example, and what actually happens when the click event happens is up to the container component:
const Button = props => {
return <button onClick={props.onClickHandler}>{props.text}</button>
}
const LoginButton = props => {
return <Button text="Login" onClickHandler={props.onClickHandler} />
}
const Container = () => {
const onClickHandler = () => {
alert('clicked')
}
return <LoginButton onClickHandler={onClickHandler} />
}
Using children
The props.children
property allows you to inject components inside other components.
The component needs to output props.children
in its JSX:
const Sidebar = props => {
return <aside>{props.children}</aside>
}
and you embed more components into it in a transparent way:
<Sidebar>
<Link title="First link" />
<Link title="Second link" />
</Sidebar>
Higher order components
When a component receives a component as a prop and returns a component, it’s called higher order component.
You can learn more about higher order components on my article React Higher Order Components.
Download my free React Handbook
More react tutorials:
- A React simple app example: fetch GitHub users information via API
- Build a simple counter with React
- VS Code setup for React development
- How to pass props to a child component via React Router
- Create an app with Electron and React
- Tutorial: create a Spreadsheet using React
- The roadmap to learn React
- Learn how to use Redux
- Getting started with JSX
- Styled Components
- Introduction to Redux Saga
- Introduction to React Router
- Introduction to React
- React Components
- The Virtual DOM
- React Events
- The React State
- React Props
- The React Fragment
- The React Context API
- React PropTypes
- React concepts: declarative
- React: How to show a different component on click
- How to loop inside React JSX
- Props vs State in React
- Should you use jQuery or React?
- How much JavaScript you need to know to use React?
- Introduction to Gatsby
- How to reference a DOM element in React
- Unidirectional Data Flow in React
- React Higher Order Components
- React Lifecycle Events
- React Concept: Immutability
- React Concept: Purity
- Introduction to React Hooks
- Introduction to create-react-app
- React Concept: Composition
- React: Presentational vs Container Components
- Code Splitting in React
- Server Side Rendering with React
- How to install React
- CSS in React
- Using SASS in React
- Handling Forms in React
- React StrictMode
- React Portals
- React Render Props
- Testing React components
- How to pass a parameter to event handlers in React
- How to handle errors in React
- How to return multiple elements in JSX
- Conditional rendering in React
- React, how to transfer props to child components
- How to get the value of an input element in React
- How to use the useState React hook
- How to use the useCallback React hook
- How to use the useEffect React hook
- How to use the useMemo React hook
- How to use the useRef React hook
- How to use the useContext React hook
- How to use the useReducer React hook
- How to connect your React app to a backend on the same origin
- The Reach Router Tutorial
- How to use the React Developer Tools
- How to learn React
- How to debug a React application
- How to render HTML in React
- How to fix the `dangerouslySetInnerHTML` did not match error in React
- How I fixed an issue with a React login form state and Browser autofill
- How to configure HTTPS in a React app on localhost
- How to fix the "cannot update a component while rendering a different component" error in React
- Can I use React hooks inside a conditional?
- Using useState with an object: how to update
- How to move around blocks of code with React and Tailwind