Understanding the useLayoutEffect Hook in React

Introduction

In React, hooks provide a powerful way to handle side effects in functional components. One such hook is useLayoutEffect, which is similar to useEffect, but with a key difference in timing. While useEffect is used to run side effects after the DOM has been updated, useLayoutEffect runs synchronously immediately after the DOM has been updated but before the browser has painted the changes to the screen. This makes it useful for scenarios where you need to measure or mutate the layout of the DOM before the user sees the changes.

In this blog, we will dive into the useLayoutEffect hook, explain how it works, and explore when to use it over useEffect.

What is useLayoutEffect?

useLayoutEffect is a React hook that runs after the DOM has been updated but before the paint. This means that it runs synchronously, which gives it the ability to read and modify the DOM immediately after changes have been made but before the changes are reflected visually in the browser.

Key Characteristics of useLayoutEffect:

• Runs synchronously after the DOM update.
• Executes before the browser renders the updated layout to the screen.
• Useful for…