Solving the useReducer Hook Error in a TypeScript Next.js Project

---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Can't use useReducer Hook with in a Typescript Next Js project

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---

Understanding the Problem

When you are using React's useReducer hook, you may encounter a common error that stems from type mismatches. This error usually looks something like this:

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

Why Does This Happen?

The core of the issue lies in how the reducer function is defined. The useReducer hook expects the reducer function to return the updated state object, but in your original version, it returns a number instead.

The Code Snippet You Provided

You shared the following snippet, which provides a good starting point for understanding where things went wrong:

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

The logic here performs the increment and decrement operations, but it does not return the state properly.

The Solution

To correctly implement the useReducer hook with TypeScript, the reducer must always return the entire state object. Here’s how to restructure your reducer function:

Step-by-Step Fix

Modify the Reducer: Change your counterReducer function so it always returns the entire state object.

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

Implementing in the Context Provider: Ensure the CounterProvider correctly uses the useReducer hook:

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

Conclusion

If you continue to face issues or have further questions regarding TypeScript and React, feel free to share your experiences or ask for help. Happy coding!