10 Best Lazy Loading JavaScript Libraries (2020 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 images, minimize the size and thus reduce the load time.

In this blog post, I’d like to introduce 10 best JavaScript libraries to lazy load large images (and other DOM elements) 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 18 2020

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

Responsive Image Lazy Load JS Library - lazysizes

Demo Download

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. Designed for high performance websites to improve the page load time and to save the bandwidth.


2. Performant Element lazy Load Library – Lozad

Performant Element lazy Load Library Lozad

Demo Download

Lozad is a small (569 bytes minified & gzipped), highly performant JavaScript library used to lazy load any html elements (e.g. images, videos, etc.) using Intersection Observer Web API.


3. Lightweight Retina Ready JS Image Lazy Load Library – Layzr.js

Layzr.js

Demo Download

Layzr.js is a lightweight yet robust JavaScript library that delays the loading of images until they’re scrolled into view.


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

Pure JavaScript Library For Lazy Loading Images – lazyload.js

Demo Download

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.


5. Easy Image Lazy Loading with blazy.js

Easy Image Lazy Loading with blazy.js

Demo Download

blazy.js is 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.


6. Modern Retina-ready Image Lazy Loader – lazyestload.js

Modern Retina-ready Image Lazy Loader - lazyestload.js

Demo Download

A modern, fast, lightweight image lazy load JavaScript library that provides 2 methods to lazy load images with support for retina and responsive images.


7. Responsive Image Lazy Load JavaScript Library – responsivelyLazy

responsivelyLazy

Demo Download

responsivelyLazy is an ultra-light javascript library which allows you to delay the loading of appropriate images based on the width of their parent containers. Help you speed up the initial page load time to provide better user experience.


8. Small Image Lazy Loader – yall.js

Small Image Lazy Loader yall.js

Demo Download

yall.js is a really small JavaScript library to lazy load images as the users scroll through your content heavy webpage. Supports srcset attribute and picture element. Based on the Intersection Observer API.


9. Tiny JavaScript Library For Progressive Image Lazy Loading – Progressively

progressively

Demo Download

Just another fast, dependency-free JavaScript library used to lazy load images with a progressive blur loading effect as you seen on Medium or Instagram.


10. Accessible Image Lazy Load In Pure JavaScript – gandul.js

Accessible Image Lazy Load In Pure JavaScript - gandul.js

Demo Download

gandul.js is a small accessible image lazy load library that works with the <a> link and supports responsive image delivery.


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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