10 Best Lazy Loading JavaScript Libraries (2024 Update)

Page speed is one of the most important ranking factors in today’s search engine optimization.

For beginners, the fastest and simplest way to speed up the web page is to optimize large resources (like images), minimize the size, and thus reduce the load time.

In this blog post, I’d like to introduce the 10 best JavaScript libraries to lazy load large web content (like images, videos, iframes, etc) within the document that makes it possible to significantly increase page speed and enhance your page rankings.

I hope you like it and help me spread the world.

Originally Published Nov 28 2017, updated Jan 27 2024

Native Lazy Loading

For Chrome users, you can use the native lazy loading feature to lazy load web resources in the modern web app.

The new loading attribute which brings native <img> and <iframe> lazy-loading to the web:

<!-- Lazy-load an offscreen image when the user scrolls near it -->
<img src="unicorn.jpg" loading="lazy" alt=".."/>
<!-- Load an image right away instead of lazy-loading -->
<img src="unicorn.jpg" loading="eager" alt=".."/>
<!-- Browser decides whether or not to lazy-load the image -->
<img src="unicorn.jpg" loading="auto" alt=".."/>
<!-- Lazy-load images in <picture>. <img> is the one driving image 
loading so <picture> and srcset fall off of that -->
<picture>
  <source media="(min-width: 40em)" srcset="big.jpg 1x, big-hd.jpg 2x">
  <source srcset="small.jpg 1x, small-hd.jpg 2x">
  <img src="fallback.jpg" loading="lazy">
</picture>
<!-- Lazy-load an image that has srcset specified -->
<img src="small.jpg"
     srcset="large.jpg 1024w, medium.jpg 640w, small.jpg 320w"
     sizes="(min-width: 36em) 33.3vw, 100vw"
     alt="A rad wolf" loading="lazy">
<!-- Lazy-load an offscreen iframe when the user scrolls near it -->
<iframe src="video-player.html" loading="lazy"></iframe>

However, you may still need a third-party JavaScript library to implement the lazy load functionality on cross-browser projects.

The 10 Best Lazy Load JavaScript Libraries:

1. Responsive Image Lazy Load JS Library – lazysizes

lazysizes is an easy yet robust JS library used to delay the loading of images (iframes, scripts, etc) until they come into view, as well as loading the appropriate sources according to the breakpoints defined in the markup to fit any screen size.

Responsive Image Lazy Load JS Library – lazysizes

[Demo] [Download]


2. Pure JavaScript Library For Lazy Loading Images – lazyload.js

lazyload.js is a stand-alone JavaScript library for lazy loading images without any dependencies. It supports the srcset attribute and with and takes best advantage from the progressive JPEG image format.

Pure JavaScript Library For Lazy Loading Images – lazyload.js

[Demo] [Download]


3. Performant Element lazy Load Library – Lozad

A small (569 bytes minified & gzipped), highly performant JavaScript library used to lazy load Html elements (e.g. images, iframes, backgrounds, etc.) using Intersection Observer Web API.

Performant Element lazy Load Library – Lozad

Demo Download


4. Lazy Load Vimeo Video Player Until You Click The Thumbnail – Vimeo LazyLoad

Vimeo LazyLoad is the sibling project of the Youtube LazyLoad that load Vimeo video player on-demand when the user clicks on the play button & thumbnail image.

Lazy Load Vimeo Video Player Until You Click The Thumbnail – Vimeo LazyLoad

Demo Download


5. Display Blurry Placeholders While Loading Images – unlazy

An SEO-friendly and framework-agnostic lazy loading library that displays a blurry image placeholder until the original image is completely loaded.

Display Blurry Placeholders While Loading Images – unlazy

Demo Download


6. Progressive Image lazy Loading With Blur Effect

A small script to progressively load images with a blur effect. The script will show your low res image with a progressive blur until the high res image has been loaded entirely.

Progressive Image lazy Loading With Blur Effect

Demo Download


7. Lazy Load iFrame Embedded Content With JavaScript – lazyframe.js

A native JavaScript library used to delay the loading of iframe content for Google Maps and Youtube/Vimeo/Vine videos.

lazyframe

Demo Download


8. Lazy Load Embed YouTube Player – youtube-iframe

A JavaScript library that easily adds Lazy Loading functionality to your Youtube videos embedded in your document.

lazy-load-embed-youtube

Demo Download


9. Load Youtube Video Only When Needed – Youtube LazyLoad

Yet another Youtube lazy loader that delays the loading of Youtube video player to improve the performance of your web page.

Youtube LazyLoad

Demo Download


10. Easy Image Lazy Loading with blazy.js

A lightweight & easy-to-use script to delay the load of images until they enter the viewport. Helpful to save the bandwidth and reduce the server requests.

Easy Image Lazy Loading with blazy.js

[Demo] [Download]


Conclusion:

This is a list of lazy load libraries implemented in vanilla JavaScript.

For jQuery users, don’t forget to check out our another list of 10 best lazy load plugins.

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