How to detect and resolve Cumulative Layout Shift (CLS) issues on a page?
When detecting Cumulative Layout Shift (CLS) issues on a page, it is usually necessary to combine tool monitoring with code optimization. Detection can be done by generating CLS scores and element shift data via Lighthouse, recording shift events in real-time using Chrome DevTools' Performance panel, or tracking the overall site performance through Google Search Console's Core Web Vitals report. The core of solving CLS issues is to reduce unexpected layout changes: - Specify dimensions: Set width and height attributes for media elements such as images and videos to avoid dynamic size adjustments; - Preload resources: Use preload or preconnect for critical resources like CSS and fonts to reduce shifts caused by loading delays; - Avoid inserting content: Do not dynamically insert ads, notifications, etc. at the top of the page; instead, reserve space or use placeholders; - Optimize font loading: Adopt font-display: swap or font-synthesis to reduce text flash shifts when fonts are not loaded. In daily maintenance, it is recommended to regularly monitor CLS values through Lighthouse, prioritize solving shift issues on the homepage and high-traffic pages, and gradually improve the user browsing experience.
