⚛ The Terrible React Anti-Pattern You Must Avoid
Tags: webdev, javascript, react, typescript
Published: 2023-10-19 16:48:45



## Introduction

In the world of React development, it's not uncommon to come across patterns that might seem convenient at first but can quickly turn into performance bottlenecks. One such anti-pattern that you should steer clear of is defining React components inside other components. This seemingly innocent practice can be one of the biggest performance killers in your application, resulting in slow rendering times and strange behaviors. In this blog post, we'll dive into the details of this anti-pattern and explore how to avoid it for a smoother and more efficient React application.

## The Anti-Pattern: Defining Components Inside Components

The anti-pattern in question can be best illustrated through a code example:

```jsx
const Component = () => {
  const ChildComponent = () => <div>Content</div>;
  return <ChildComponent />;
};
```

In this code snippet, we define `ChildComponent` within `Component`. While this may seem harmless, it leads to some undesirable consequences.

The Problem with This Approach

1. **Recreating ChildComponent:** When `Component` is re-rendered, React will create a new instance of `ChildComponent` every time. This means that the "previous" `ChildComponent` will be removed, and the "next" one will be mounted. This behavior is terrible for performance, as it introduces unnecessary overhead and slows down your application.

2. **State Disappearance:** If `ChildComponent` has its own state, it will lose that state every time it is recreated during a re-render of `Component`. This can lead to unexpected and erroneous behaviors in your application.

## The Solution: Defining Components Outside Components

To avoid this performance-killing anti-pattern, it's essential to define your components outside the scope of other components. Here's how you should structure your code:

```jsx
const ChildComponent = () => <div>Content</div>;

const Component = () => {
  return <ChildComponent />;
};
```

By defining `ChildComponent` outside of `Component`, you ensure that it won't be recreated with every re-render of `Component`. Instead, it behaves as a normal component and re-renders only when its props or state change.

## Benefits of This Approach

1. **Improved Performance:** Defining components outside other components reduces unnecessary re-creations, resulting in improved rendering performance. Your application will render faster and provide a smoother user experience.

2. **Consistent State:** If `ChildComponent` has state, it will maintain that state across re-renders, ensuring consistent behavior and avoiding potential bugs.

## Conclusion

In the world of React development, it's crucial to be mindful of anti-patterns that can harm your application's performance. Defining React components inside others is one such anti-pattern that should be avoided at all costs. By adhering to best practices and defining components outside of other components, you can ensure that your application performs optimally and provides a consistent user experience. So, remember, if you want to avoid applications with horrible performance and weird behaviors, never define React components inside others. Your users will thank you for it!

Happy coding! 🎉💻✨

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