From ‘watch’ to ‘useWatch’: The Critical React Hook Form Update for React 19

Introduction

This article highlights the crucial update in React Hook Form for React 19, focusing on the transition from the `watch` API to the `useWatch` hook. This change is vital to prevent re-rendering issues in your React components after upgrading to React 19. Understanding and implementing this update is essential for a smooth transition and maintaining the functionality of your forms.

What Changed?

In React 19, the `watch` API in React Hook Form has been replaced with `useWatch`. This change addresses performance issues and provides more control over component re-renders. The `useWatch` hook allows you to selectively subscribe to specific form values, optimizing performance and preventing unnecessary re-renders.

Why the Change?

The primary reason for this change is to improve performance. The old `watch` API could trigger unnecessary re-renders, especially in complex forms with many fields. By using `useWatch`, you can precisely specify which form values a component should track, leading to significant performance gains.

How to Migrate

Migrating from `watch` to `useWatch` is straightforward. Here’s a step-by-step guide:

• Replace all instances of `watch()` with `useWatch()`.
• Specify the fields you want to watch using the `name` property.
• Test your components thoroughly to ensure they function as expected.

Example

Here’s an example of how to use `useWatch`:

import { useForm, useWatch } from 'react-hook-form';

function MyComponent() {
  const { control } = useForm();
  const firstName = useWatch({ control, name: 'firstName' });

  return (
    <div>
      <p>First Name: {firstName}</p>
    </div>
  );
}

Conclusion

The transition from `watch` to `useWatch` in React Hook Form for React 19 is a critical update that improves performance and provides more control over component re-renders. Make sure to update your components to take advantage of these improvements and ensure a smooth transition to React 19. Remember to test your forms after the migration to guarantee that everything works correctly.