How to Reduce Cumulative Layout Shift on Dynamic Content
Cumulative Layout Shift (CLS) is a crucial metric in the realm of web performance, particularly when it comes to dynamic content. This metric measures the visual stability of a webpage and indicates how much a page layout shifts during loading. High CLS can lead to a poor user experience, as unexpected shifts can cause frustration when users click links or images only to have them move unexpectedly. Here’s how to effectively reduce CLS on dynamic content.
1. Reserve Space for Dynamic Content
One of the best strategies to minimize CLS is to reserve space in the layout for dynamic elements. When adding images, videos, and advertisements, always define their width and height using CSS or HTML attributes. This practice allows the browser to allocate the appropriate space before the content loads, preventing layout shifts.
2. Optimize Images and Videos
Images and videos often contribute significantly to CLS when they are not optimized correctly. Use well-compressed images in formats like WebP and ensure that their dimensions are defined in your markup. For videos, consider using a placeholder in the place of the video element. This ensures that the space is reserved before the video loads, stabilizing the layout.
3. Load Fonts Efficiently
Improper loading of fonts can lead to a phenomenon known as "FOUC" (Flash of Unstyled Content), resulting in layout shifts. To prevent this, consider using the 'font-display: swap' CSS property. This allows text to remain visible while the font is loading, reducing unexpected shifts in text layout.
4. Limit Third-Party Scripting
Third-party scripts can frequently lead to layout changes as they load and render. Be discerning about the third-party content you include on your pages. Use asynchronous loading for scripts and prioritize those that are essential. Additionally, evaluate the impact of third-party ads and consider hosting them in a way that prevents layout shifts.
5. Use Placeholder Elements
For dynamic content that loads after the page is rendered, such as comments or social media widgets, use placeholder elements that maintain the overall structure of the page. This not only enhances the visual flow but also ensures a more stable user experience as additional content loads.
6. Test with Tools
After implementing changes, it’s crucial to test your webpage to measure its CLS score. Utilize tools like Google’s Lighthouse, PageSpeed Insights, or the Web Vitals extension to identify areas of improvement. Regular testing will help you keep your CLS under control and ensure an optimized user experience.
7. Implement Lazy Loading Wisely
Lazy loading is an effective way to improve page load times by deferring the loading of offscreen images and resources. However, if not implemented correctly, it can cause layout shifts. Ensure to implement lazy loading in a way that doesn't disrupt content stability. Use the ‘loading="lazy"’ attribute on images and iframes to help mitigate this issue.
Conclusion
Reducing Cumulative Layout Shift on dynamic content is vital for maintaining a positive user experience and improving search engine optimization. By reserving space for content, optimizing images and videos, loading fonts efficiently, limiting third-party scripts, and using placeholders strategically, you can significantly lower your CLS scores. Always keep testing and refining your approach for the best results. A stable, uninterrupted layout not only enhances user satisfaction but can also positively impact your website's rankings in search results.