CSS Scroll Animation Last Updated : 12 Sep, 2024 Comments Improve Suggest changes Like Article Like Report CSS scroll animations are used to make webpages more exciting and engaging to the users by applying animations on scroll. Scroll animations assist in directing the users’ attention, enhance the usability of the site, and bring a sense of depth, without overloading the user. In this article, we will see the simplest strategies for using CSS and JavaScript to create the transition effect.What are Scroll Animations?Scroll animations refer to the movement or transformation of elements as the user scrolls through the webpage. These animations can include fading, sliding, scaling, or rotating elements into view. They are widely used in modern web design to make websites feel more interactive and visually appealing.Common Use Cases:Highlighting key sections as they come into view.Creating parallax effects where background and foreground elements scroll at different speeds.Revealing content gradually, such as text or images, as the user scrolls down the page.How Scroll Animations Work?CSS scroll animations are based on applying the transition to elements that start once a user scrolls to a certain point on the page. This is usually achieved by applying CSS transition and JavaScript to identify scroll events.Performance ConsiderationsScroll animations are known to affect the level of performance of a webpage if poorly optimized. Here are some tips to ensure your animations run smoothly:Use Hardware-Accelerated Properties: When animating, use properties like transform and opacity that are hardware-accelerated by browsers. It is recommended not to use properties such as top, left or height since they cause layout calculations and hence are expensive.Debounce Scroll Events: Scroll events happen often which might cause problems with performance. To minimize the execution of the scroll event handler, one can consider the use of debounce function or the requestAnimationFrame.Lazy Load Animations: Animate only those elements which are in the viewport. This decreases the number of active animations and thus makes the work much faster and more efficient especially on large pages.Example: The example below shows how a basic scroll animation with a fade in can be created: a box element gradually appears and scrolls in from the bottom of the page. HTML <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Scroll Animation Example</title> <style> body { font-family: Arial, sans-serif; height: 200vh; /* This makes the page tall enough to scroll */ margin: 0; padding: 0; background-color: #f4f4f4; } h1 { text-align: center; margin-top: 50px; } .box { width: 100px; height: 100px; background-color: #3498db; margin: 50px auto; border-radius: 10px; opacity: 0; transform: translateY(50px); transition: transform 0.5s ease, opacity 0.5s ease; } /* This class will trigger the animation */ .show { opacity: 1; transform: translateY(0); } </style> </head> <body> <h1>Scroll Down to See the Box</h1> <div class="box" id="box"></div> <script> window.addEventListener('scroll', function () { const box = document.getElementById('box'); const boxPosition = box.getBoundingClientRect().top; // Get box position relative to the viewport const windowHeight = window.innerHeight; // Get the height of the viewport // If the box is within the visible part of the screen, //trigger the animation if (boxPosition < windowHeight - 50) { box.classList.add('show'); } else { box.classList.remove('show'); } }); </script> </body> </html> Output: Comment More infoAdvertise with us Next Article CSS Introduction G gmoksi039 Follow Improve Article Tags : Web Technologies CSS Similar Reads CSS Tutorial CSS stands for Cascading Style Sheets. 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