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

The React Hook Form library is a powerful tool for managing forms in React applications. However, upgrading to React 19 introduces a breaking change that can cause unexpected behavior if you're not aware of it. This article explains the critical update from `watch` to `useWatch` and how to adapt your code.

Many React developers have faced the issue that the React Hook Form components stopped re-rendering after upgrading to React 19. This is due to the new API, `useWatch`, that was not present in the previous versions.

Understanding the Change

In previous versions of React Hook Form, the `watch` function was used to subscribe to form values and trigger re-renders when those values changed. However, React 19 introduces a new hook called `useWatch`, which provides a more controlled and predictable way to watch form values.

The primary difference is that `useWatch` explicitly subscribes your component to the specific form values you specify. This avoids unnecessary re-renders when other form values change, leading to improved performance.

Implementing `useWatch`

To migrate from `watch` to `useWatch`, you need to update your component to use the new hook. Here's a basic example:

• Import `useWatch` from 'react-hook-form'
• Replace the watch function with `useWatch`
• Specify the control and name properties

For instance, if you were previously watching a field called 'firstName' using `watch('firstName')`, you would now use `useWatch({ control, name: 'firstName' })`.

Benefits of `useWatch`

Using `useWatch` offers several advantages:

• Improved performance by reducing unnecessary re-renders.
• More predictable behavior by explicitly subscribing to specific form values.
• Better control over when your component re-renders.

By understanding and implementing this critical update, you can ensure that your React Hook Form components work seamlessly with React 19 and benefit from improved performance and predictability.