What's the difference between ReactNode vs React.Element

When working with TypeScript in ReactJs, understanding the nuances between ReactNode and React.Element is crucial for writing clean, type-safe code. Ealier in my career, i often misuse or interchange the usage of ReactNode and React.Element. But these types represent different aspects of React content, and their appropriate usage can significantly impact your project's maintainability and performance. Let's talk about this in details:

What is ReactNode?

ReactNode is a comprehensive type that encompasses any type of React content that can be rendered. This includes:

• React elements (created using JSX)
• Strings
• Numbers
• Arrays or fragments of the above
• null
• undefined
• Booleans

What is React.Element?

React.Element on the other hand, is a more specific type that represents a React element. This is the object returned by React.createElement() or JSX expressions. It has a defined structure with type, props, and key properties.

Now let's take a look at key differences between both:

Key Differences

Feature	ReactNode	React.Element
Scope	Includes React.Element and other types.	Represents only React elements.
Usage	For component children or props accepting various content.	When you specifically need a React element.
Nullability	Can be null or undefined.	Cannot be null or undefined.
Type Safety	Provides less type safety compared to React.Element.	Provides more type safety.

When to Use ReactNode

• Defining types for children props: When a component can accept various types of content, use ReactNode.
• Working with flexible content: If your component needs to render different types of content, ReactNode is suitable.

Example:

interface Props {
  children: React.ReactNode;
}

const Container: React.FC<Props> = ({ children }) => {
  return <div>{children}</div>;
};

When to Use React.Element

• Ensuring type safety: When you need to guarantee that a prop is a React element, use React.Element.
• Working with higher-order components or render props: If you're manipulating React elements, React.Element is appropriate.

Example:

interface Props {
  element: React.ReactElement;
}

const ElementWrapper: React.FC<Props> = ({ element }) => {
  return <div className="wrapper">{React.cloneElement(element, { className: 'modified' })}</div>;
};

Best Practices

• Default to ReactNode: When in doubt, use ReactNode for component children.
• Use React.Element for specificity: If you need to ensure a prop is a React element, use React.Element.
• Consider nullability: Handle null and undefined cases when using ReactNode.
• Type narrowing: If necessary, narrow ReactNode to React.ReactElement for specific operations.

Conclusion

By understanding the differences between ReactNode and React.Element, you can write more type-safe and maintainable React components. Choose the appropriate type based on your specific needs to ensure your code is both flexible and robust.