How to Fix Type is not assignable to type ReactNode Error in React Router?

Learn how to resolve the common TypeScript error "Type '() = JSX.Element' is not assignable to type 'ReactNode'" in React Router applications.
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If you're working with TypeScript and React Router, you might encounter an error message that says, "Type '() => JSX.Element' is not assignable to type 'ReactNode'". This error typically arises when you're trying to use a functional component within your router configuration.

Understanding the Error

The error message "Type '() => JSX.Element' is not assignable to type 'ReactNode'" usually indicates a type mismatch. In TypeScript, ReactNode is a union type that encompasses all possible return values of a React component, whether it's a JSX element, a string, or even null.

However, TypeScript expects the rendered component to be a ReactNode but finds a function returning a JSX element (i.e., () => <JSX.Element />). This discrepancy causes the type error.

Common Scenario

The scenario below demonstrates a typical usage that results in this error:

[[See Video to Reveal this Text or Code Snippet]]

In this setup, the element prop of the Route is assigned a function that returns a JSX element, which is not the expected type (ReactNode).

Solution

The key to resolving this error is ensuring the element prop receives a valid ReactNode rather than a function that returns one. Replace the anonymous functions with direct JSX elements:

[[See Video to Reveal this Text or Code Snippet]]

By doing so, you ensure that the element prop receives JSX.Element, which is valid ReactNode. This change eliminates the type error and ensures type safety throughout your application.

Conclusion

TypeScript's type safety aims to prevent potential runtime errors, and adhering to its rules enhances the robustness of your React applications. When encountering the "Type '() => JSX.Element' is not assignable to type 'ReactNode'" error, remember to ensure that your Route components' element props directly receive JSX elements, not functions that return them.

By following this guideline, you'll keep your codebase clean, maintainable, and free from such type errors.