Resolving the Expected 0 type arguments, but got 1 Error in TypeScript React Hook useState()

Learn how to fix the TypeScript error "Expected 0 type arguments, but got 1" when creating a custom hook in React. Follow our step-by-step guide on using `useForm` effectively.
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How to Fix "Expected 0 Type Arguments, but Got 1" Error in TypeScript React Hook useState()

When working with TypeScript and React, encountering errors can be frustrating, especially for newcomers. One common error that developers often face is: "Expected 0 type arguments, but got 1." This error typically occurs when creating a custom hook with TypeScript. In this post, we will go through what this error means and how you can resolve it effectively.

Understanding the Problem

In your TypeScript React application, you've created a custom hook named useForm, which utilizes the useState hook. Here's a snippet of the code in question:

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

When trying to use this hook, TypeScript throws the error:

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

This indicates that the useForm function is not set up to accept type arguments correctly.

Why This Error Occurs

The root cause of this error lies in the signature of your useForm function. As it currently stands, the function is not recognized as a generic function, which means it does not accept type parameters when called. To fix this, you'll need to modify the function definition.

Solution: Making useForm a Generic Function

To resolve the error, you should refactor your useForm hook to accept generic types. Here’s how you can do that:

Step 1: Modify the Hook Definition

Update the definition of your useForm function to allow for generics:

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

Step 2: Use the Hook in Your Component

Now that your useForm function supports types, you can use it in your component without running into type issues:

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

Key Changes Explained

Generic Syntax: The <T extends Record<string, unknown>> syntax allows your hook to accept any object type.

Improved setValues Functionality: The useCallback hook is utilized for the handleChange function to prevent unnecessary re-renders and provide better performance.

Conclusion

By following these steps, you can resolve the error "Expected 0 type arguments, but got 1" when working with TypeScript and custom hooks in React. Creating more flexible and type-safe custom hooks not only eliminates compilation errors but also improves the overall quality of your code.

If you have further questions or topics related to TypeScript and React that you'd like to explore, feel free to reach out. Happy coding!