Resolving Issues with Lazy-Loaded Content

Making Lazy-Loaded Content Accessible for Google

Deferring the loading of non-critical or non-visible content, commonly known as "lazy loading", is a powerful technique for improving website performance and user experience. By loading resources only when they are needed, you can significantly reduce page load times and conserve bandwidth.

However, if not implemented correctly, lazy loading can inadvertently hide content from Google, preventing it from being crawled and indexed. This document outlines best practices to ensure your lazy-loaded content is discoverable by search engines.

1. Load Content When It's Visible in the Viewport

The fundamental principle for SEO-friendly lazy loading is to load all relevant content the moment it enters the user's viewport. This means that as the user scrolls through your page, content just below the fold should begin loading automatically.

Let's illustrate this with an example. Imagine a blog post featuring several images. Instead of loading all images upfront, we can lazy-load them as the user scrolls:

<img src="placeholder.jpg" data-src="actual-image.jpg" class="lazy-image" alt="Descriptive alt text">

In this example:

• placeholder.jpg is a lightweight placeholder image displayed immediately.

• data-src attribute stores the URL of the actual image to be lazy-loaded.

• lazy-image class is used to target these images with JavaScript.

Now, let's implement lazy loading using the Intersection Observer API:

const images = document.querySelectorAll('.lazy-image');

const observer = new IntersectionObserver((entries) => {
  entries.forEach((entry) => {
    if (entry.isIntersecting) {
      const image = entry.target;
      image.src = image.dataset.src;
      observer.unobserve(image);
    }
  });
});

images.forEach((image) => observer.observe(image));

This script does the following:

1. Selects all images with the lazy-image class.

2. Creates an IntersectionObserver to monitor these images.

3. When an image enters the viewport (isIntersecting), it replaces the src with the URL stored in data-src.

4. Once an image is loaded, it's removed from observation (unobserve) to avoid unnecessary processing.

This ensures that Googlebot, upon rendering your page, can discover and index these images as they would be loaded within the user's viewport.

Alternatives for Lazy Loading

• Native lazy loading: Modern browsers support native lazy loading using the loading="lazy" attribute on images and iframes. This simplifies implementation significantly.

<img src="image.jpg" loading="lazy" alt="...">
<iframe src="video.mp4" loading="lazy"></iframe>

• JavaScript libraries: Several libraries like lazysizes or lozad.js offer efficient and feature-rich lazy loading solutions, handling various content types and optimization techniques.

Caution: Avoid applying lazy loading to content likely to be immediately visible upon page load. This can lead to a noticeable delay in content display for the user, negating the benefits of lazy loading.

2. Support Paginated Loading for Infinite Scroll

Infinite scrolling, while providing a seamless browsing experience, can pose challenges for SEO. If not implemented correctly, content loaded via infinite scroll may be hidden from Google.

To ensure your infinite scroll implementation is SEO-friendly, prioritize paginated loading. This means:

1. Unique URLs for each section: Each section loaded via infinite scroll should have a unique URL, enabling direct access and sharing.

2. History API: Use the History API to update the URL as the user scrolls, reflecting the currently loaded content section. This allows users to share links to specific sections and improves the back button behavior.

For instance, imagine an e-commerce site with infinite scrolling for product listings. Instead of a single URL, each batch of products loaded upon scrolling should have a distinct URL like:

• https://example.com/products?page=1

• https://example.com/products?page=2

• and so on...

Implementing pagination ensures that Google can:

• Crawl and index each section of your content individually.

• Understand the context of each section through the unique URL.

• Display relevant links in search results, directing users to specific content sections within your infinite scroll implementation.

3. Test Your Implementation Thoroughly

Once you have implemented lazy loading and pagination for your content, thoroughly test its functionality:

1. URL Inspection Tool: Utilize the URL Inspection Tool in Google Search Console to see how Googlebot renders your pages. Verify if all images and content are being loaded correctly.

2. Inspect Rendered HTML: Right-click on your page and select "Inspect" or "View Page Source" (depending on your browser). Within the developer tools, examine the rendered HTML to ensure:

   • Lazy-loaded images have their src attributes populated with the correct image URLs.

   • Content loaded via infinite scroll is present within the HTML structure.

3. Manual Testing: Scroll through your pages and observe if content loads as expected without delays or errors.

By following these guidelines and testing rigorously, you can reap the performance benefits of lazy loading and infinite scrolling while ensuring your content remains accessible and discoverable by Google.