Fixing the TypeError: validation is not a function in React.js Forms

---

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

If you've ever worked with forms in React, you might have encountered the frustrating error: TypeError: validation is not a function. This error typically occurs when you've integrated form validation logic and linked it to a custom hook, but something goes amiss in the callback structure. Today, we'll dive into understanding why this happens and how to fix it effectively.

The Problem

The error arises when the system fails to recognize the validation function, which is critical for form submissions. In the context provided, the developer is trying to validate form inputs like name, email, password, etc., using a custom hook (useForm). However, upon submission, the application throws the validation error, indicating it is not properly defined or passed.

Code Overview

The problem lies in how the useForm hook is being called. In the initial implementation, it appears like this:

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

In this code block, the validation function is correctly defined but not passed as intended.

The Solution

To rectify the issue, we need to ensure both the callback and validation functions are properly defined and passed to the useForm hook. Below, we'll break down the steps to fix the code.

Step 1: Define the Callback Function

First, you need to define a callback function, which will be executed upon successful submission (when there are no validation errors).

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

Step 2: Passing the Functions into useForm

Next, invoke the useForm hook correctly by passing both the callback and the validation functions.

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

Incorporating both functions will ensure that the useForm is aware of how to handle form submission and validation seamlessly.

Complete Example with Fixes

Here is how the updated Signup component should look:

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

Final Thoughts

By properly structuring the usage of your custom hook, you eliminate the TypeError: validation is not a function error and enhance your form's reliability. Remember, whenever you're passing functions to hooks, ensure that all dependencies are correctly listed and defined. This will help you maintain cleaner, more efficient, and error-free React applications.

In conclusion, the key takeaway from this article is the importance of passing both callback and validation functions to your custom hooks to avoid unexpected errors and ensure smooth functionality in your forms.