Five Advance Ways to Lazy Load Images for Better Web

Lazy loading images is an essential technique for optimizing web performance. By deferring the loading of images until they are actually needed, you can significantly reduce initial page load times, save bandwidth, and improve user experience. Here, we will explore five advanced ways to implement lazy loading for images.

1. Native Lazy Loading

What is it?
Native lazy loading is a built-in browser feature that allows you to defer the loading of images until they are about to enter the viewport. This method requires minimal effort and no additional JavaScript libraries.

How to implement it:
Simply add the loading="lazy" attribute to your <img> tags.

<img src="image.jpg" alt="Description" loading="lazy">

Advantages:

1. Simplicity: Requires minimal code changes.
2. Performance: Leverages native browser capabilities for optimal performance.
3. Compatibility: Supported by most modern browsers.

1. Limited control: Less customization compared to JavaScript libraries.
2. Browser support: Not supported by all browsers, especially older ones.

2. Intersection Observer API

What is it?
The Intersection Observer API allows you to asynchronously observe changes in the intersection of a target element with an ancestor element or the viewport.

How to implement it:
Use JavaScript to create an intersection observer and apply it to your images.

<img data-src="image.jpg" alt="Description" class="lazy">

<script>
  document.addEventListener("DOMContentLoaded", function() {
    const lazyImages = document.querySelectorAll('img.lazy');
    const observer = new IntersectionObserver((entries, observer) => {
      entries.forEach(entry => {
        if (entry.isIntersecting) {
          const img = entry.target;
          img.src = img.dataset.src;
          img.classList.remove('lazy');
          observer.unobserve(img);
        }
      });
    });

    lazyImages.forEach(img => {
      observer.observe(img);
    });
  });
</script>

Advantages:

1. Flexibility: Provides more control and customization options.
2. Performance: Efficient and optimized for modern web development.

1. Complexity: Requires more code and understanding of the API.
2. Compatibility: Limited to modern browsers that support the Intersection Observer API.

3. Lazy Load Libraries

What is it?
Several JavaScript libraries simplify the implementation of lazy loading for images, providing additional features and better browser support.

How to implement it:
One popular library is lazysizes. Include the library in your project and use its classes.

<script src="https://cdnjs.cloudflare.com/ajax/libs/lazysizes/5.3.2/lazysizes.min.js" async></script>
<img data-src="image.jpg" alt="Description" class="lazyload">

Advantages:

1. Ease of use: Libraries handle the complexity for you.
2. Features: Often include additional features like responsive images and placeholders.
3. Community support: Well-maintained with good documentation.

1. Dependency: Adds external dependency to your project.
2. File size: Increases the overall size of your project.

4. Lazy Loading with JavaScript Event Listeners

What is it?
This method uses JavaScript event listeners to load images only when they come into the viewport.

How to implement it:
Write custom JavaScript to listen for scroll events and load images accordingly.

<img data-src="image.jpg" alt="Description" class="lazy">

<script>
  document.addEventListener("DOMContentLoaded", function() {
    const lazyImages = document.querySelectorAll('img.lazy');
    const loadImage = function() {
      lazyImages.forEach(img => {
        if (img.getBoundingClientRect().top < window.innerHeight && img.getBoundingClientRect().bottom > 0) {
          img.src = img.dataset.src;
          img.classList.remove('lazy');
        }
      });
    };

    window.addEventListener('scroll', loadImage);
    window.addEventListener('resize', loadImage);
    window.addEventListener('orientationchange', loadImage);
  });
</script>

Advantages:

1. Control: Full control over the lazy loading behavior.
2. Customization: Easily customized to fit specific needs.

1. Performance: Can be less efficient and may cause performance issues if not optimized.
2. Complexity: Requires more code and careful handling of events.

5. Placeholder Images

What is it?
Placeholder images are low-resolution or blurred versions of the original images that are initially loaded, providing a quick visual feedback to users.

How to implement it:
Use a combination of low-resolution placeholders and lazy loading techniques.

<img src="placeholder.jpg" data-src="image.jpg" alt="Description" class="lazy">

<script>
  document.addEventListener("DOMContentLoaded", function() {
    const lazyImages = document.querySelectorAll('img.lazy');
    lazyImages.forEach(img => {
      const src = img.dataset.src;
      img.src = src;
      img.onload = () => {
        img.classList.remove('lazy');
      };
    });
  });
</script>

Advantages:

1. User experience: Improves perceived performance by showing a placeholder.
2. Visual feedback: Provides immediate visual feedback while the full image loads.

1. Additional work: Requires creating and managing placeholder images.
2. Complexity: More complex to implement and manage.

Conclusion

Lazy loading images is a crucial optimization technique for modern web development. Each method discussed has its own advantages and drawbacks, so the best approach depends on your specific requirements and the context of your project. Native lazy loading is the simplest, while the Intersection Observer API and lazy load libraries offer more control and features. JavaScript event listeners and placeholder images provide additional customization and visual feedback options. Implementing lazy loading will help you enhance the performance, efficiency, and user experience of your website.

By choosing the right lazy loading strategy, you can create faster, more efficient websites that provide a better experience for your users.

Thanks you ☺️. Happy coding 👍.