Differences between stateful and stateless components in React

Stateful components are those that have internal state or data that can change over time. They use class and have a render() method that returns the content. Whenever the state of the component changes, the render() method is called again to update the user interface.

On the other hand, stateless components do not have internal state. They use function and accept props as input parameters. They return the content as JSX code.

Choosing between stateful and stateless components

In general, you should use stateful components whenever you need to manage state or an internal data in your component. For example, if you need to create a form where the user can input data, you will likely need a stateful component to keep track of the form data as it changes.

On the other hand, if you have a component that simply renders content without requiring any state modifications, you can use a stateless component. This can help improve performance since they are simpler.

Example of stateful and stateless components

Let's say we are creating a simple todo list application. We want to create a component that displays each todo item. Here's how we could create both a stateful and a stateless version:

Stateful TodoItem Component

{
`class TodoItem extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      completed:
 false    }
;
  }
  handleCompleted = () => {
    this.setState({
 completed:
 !this.state.completed }
);
  }
;
  render() {
    return (          );
  }
}
`}

Stateless TodoItem Component

{
`const TodoItem = (props) => {
  const [completed, setCompleted] = React.useState(false);
  const handleCompleted = () => {
    setCompleted(!completed);
  }
;
  return (      );
}
`}

In this example, we defined both a stateful and a stateless version of the same TodoItem component. The stateful version uses a class to manage the completed state of the component and updates the user interface whenever the state changes. The stateless version uses useState() Hook to manage the completed state and returns the content without modifying its internal state.

The choice between using stateful or stateless components in this example largely depends on the complexity of the component and the project requirements.

Conclusion

In summary, stateful and stateless components differ in the way they manage state and data. Stateful components are used when we need to manage state – whenever we update the state and need to re-render, the component updates. Stateless components, on the other hand, do not require state management and are simpler. When creating a React application, it's important to understand when to use stateful and stateless components to ensure efficient rendering and improve performance.

References

1. Function and class components - React documentation
2. Stateful vs. Stateless React Components - Josh Black