Understanding useLayoutEffect vs useEffect in React

When working with React, you’ll often need to perform side effects in your functional components. React provides two hooks for this purpose: useEffect and useLayoutEffect. While they serve a similar purpose, their timing and use cases differ significantly. Let’s explore these differences to help you choose the right hook for your needs.

Understanding useLayoutEffect vs useEffect in React

useEffect

The useEffect hook is the most commonly used hook for handling side effects in React. It runs after the component renders, which means it executes after the DOM has been updated. This makes it ideal for tasks like fetching data, setting up subscriptions, or manually changing the DOM.

Key Points:

• Runs asynchronously after the DOM update.
• Suitable for tasks that do not require immediate DOM measurement or manipulation.
• And the most important one, does not block the browser’s painting process.

useLayoutEffect

The useLayoutEffect hook is similar to useEffect, but it runs synchronously after all DOM mutations but before the browser has painted. This means it fires after the DOM is updated but before the browser repaints the screen. useLayoutEffect is useful for scenarios where you need to read layout information from the DOM…