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Should you really ditch JavaScript libraries for native lazy loading solutions?

Martin Splitt Feb 25, 2021 ★★★ FR
Should you really ditch JavaScript libraries for native lazy loading solutions?

Official statement

For lazy loading images, it is recommended to either use the browser's native lazy loading with the 'loading=lazy' attribute, or a solution based on Intersection Observer rather than libraries that can cause issues.
50:43
🎥 Source video

Extracted from a Google Search Central video

⏱ 1704h03 💬 EN 📅 25/02/2021 ✂ 15 statements
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  14. 86:54 Is JavaScript really wreaking havoc on your Core Web Vitals?
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Official statement from (5 years ago)
⚠ A more recent statement exists on this topic Is the HTML loading=lazy attribute really enough to prevent indexation issues? Martin Splitt · August 21, 2025 View statement →
TL;DR

Google explicitly recommends using the native `loading=lazy` attribute or Intersection Observer for lazy loading images, rather than third-party JavaScript libraries. These libraries can block rendering or create crawling issues. For SEO, this means auditing existing implementations and migrating to solutions that are detectable by Googlebot. However, some modern libraries can still perform well if configured correctly.

What you need to understand

Why does Google warn against lazy loading libraries?

The main problem with JavaScript libraries for lazy loading lies in their mode of operation. Many rely on scroll events or complex detections that do not always trigger correctly during Googlebot's crawl. The bot does not scroll a page like a human; it simulates an initial viewport and then analyzes the rendered DOM.

As a result: an image configured for lazy loading via a JS library may remain invisible to the crawler if it is not within the initial viewport. Worse still, some libraries block the critical rendering path by injecting heavy JavaScript before essential resources are loaded. Google has said numerous times: anything that delays the First Contentful Paint or LCP is problematic.

What exactly is native lazy loading and Intersection Observer?

Native lazy loading (`loading="lazy"`) is an HTML5 attribute that all modern browsers have understood since 2019-2020. You add it to an `` or `'; }