Native Lazyload

Description

Lazy-loads media using the native browser feature. Learn more about the new loading attribute or view the WordPress core ticket where inclusion of a similar implementation in WordPress core itself is being discussed.

If the loading attribute is not supported by the browser, the plugin falls back to a JavaScript solution based on IntersectionObserver. For the case that JavaScript is disabled, but the loading attribute is supported by the browser, a noscript variant of the respective element will be added that also includes the loading attribute without any further changes.

“Native” means “Fast”

If you have found your way over here, you are probably aware of how crucial performance is for a website’s user experience and success. You might also know that lazy-loading is a key feature to improve said performance. However, the solutions for lazy-loading so far still added a bit of overhead themselves, since they relied on loading, parsing and running custom JavaScript logic, that may be more or less heavy on performance.

This plugin largely does away with this pattern. It relies on the new loading attribute, which makes lazy-loading a native browser functionality. The attribute is already supported by Chrome, and will be rolled out to other browsers over time. The solution being “native” means that it does not rely on custom JavaScript logic, and thus is more lightweight. And “more lightweight” means “faster”.

Last but not least, a neat thing to keep in mind is that this plugin will essentially improve itself over time, as more browsers roll out support for the loading attribute.

Usage

Just activate the plugin, and all your images and iframes in post content will be loaded lazily.

Credit

This plugin is partly based on logic from WP Rig as well as recommendations from web.dev and developers.google.com.

Installation

  1. Upload the entire native-lazyload folder to the /wp-content/plugins/ directory or download it through the WordPress backend.
  2. Activate the plugin through the ‘Plugins’ menu in WordPress.

FAQ

Where are the plugin’s settings?

This plugin does not have a settings screen. Just by activating it, the plugin will work.

How can I prevent an image or iframe from being loaded lazily?

You can add a class skip-lazy to indicate to the plugin you would like to skip lazy-loading for this image or iframe.

This plugin still loads an extra JavaScript file! I don’t want that.

This is perfectly fair. Note that the plugin only loads the JavaScript file as a fallback for when the user’s browser does not support the native loading attribute yet. The file includes logic to still autoload the image in a non-native way. If you prefer to purely rely on the loading attribute and not provide any fallback, you can easily disable it by adding a line add_filter( 'native_lazyload_fallback_script_enabled', '__return_false' ) somewhere in your site’s codebase.

Does this work with AMP?

If you use AMP, you don’t actually need this, since AMP intelligently lazy-loads media out of the box. Still, the plugin is built in a way that it will not break AMP compatibility, just to make sure.

Where should I submit my support request?

For regular support requests, please use the wordpress.org support forums. If you have a technical issue with the plugin where you already have more insight on how to fix it, you can also open an issue on Github instead.

How can I contribute to the plugin?

If you have some ideas to improve the plugin or to solve a bug, feel free to raise an issue or submit a pull request in the Github repository for the plugin. Please stick to the contributing guidelines.

You can also contribute to the plugin by translating it. Simply visit translate.wordpress.org to get started.

Reviews

February 27, 2020
First, did not break my site and it did lazyload most of the page images. It does not lazyload images if they are served from a different host. Example, unbounce, etc. I will add another caveat, all of my images and their versions are always carefully resized and highly compressed. Checked with lighthouse and my score took a hit downwards. 13 points down on performance score. I tested on my Staging area, uncached. FCP went from 2.1s to 4.2s, all of the other metrics, including time to interactive, CPU idle, speed index and First Meaningful Paint took a dive. I will chuck this to I was already hyperoptimized and lazy loading is not truly needed on my site/s. But I would advise others to try it out (not on their live site) and test speed with Google Lighthouse before and after.
February 17, 2020
Seems to work well. On browsers that don't support lazy loading, it doesn't seem to load the images as soon as I would like. As in there can be a bit of a delay between scrolling and the image appearing on screen. Not to bad though. Not going to worry about it as native image loading is the way of the future and will be implemented into more browsers.
February 15, 2020
I did a test with only wp supercache and this plugin, i have a lot images on my website, test on a page: was at 15s, moved to 7s (page with 9 big images) test on Gtmetrix I like the idea of plug and play and it works Thank you to the authors for this plugin
January 30, 2020
So far i never have single issue with this plugin. I highly recommend it to newbies because this plugin works without breaking AMP.
December 26, 2019
Was using regular lazy load plugins, but this thing takes it up a notch. Not just because of the native lazy load, which in itself is absolutely brilliant an an idea whose time had come, but I just like it that it doens't clutter the backend with unnecessary pages. Does what it says. Activate and forget.
December 6, 2019
Initially some minor issues with IE11 but it is now fixed. Also google's lazy load attribute has some more smarts built into it then the typical lazy load scripts you are use to using, so you may be a little confused when it looks like nothing is happening and images are not being lazy loaded, but they are! just in a more advanced and discreet way, use dev tools to see for yourself. Bonus: Once IE11 is finally decommissioned, you'll be able to disable this plugin, by then all browsers and WordPress should have native support for the new lazy-load attribute.
Read all 27 reviews

Contributors & Developers

“Native Lazyload” is open source software. The following people have contributed to this plugin.

Contributors

“Native Lazyload” has been translated into 15 locales. Thank you to the translators for their contributions.

Translate “Native Lazyload” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.

Changelog

1.0.2

  • Fix broken images which are using data URI scheme (e.g. base64-encoded images). Props ieim.
  • Fix images in IE 11 not being loaded until the user starts scrolling. Props Soean.
  • Fix image loading script not working in IE10 and other browsers that do not support dataset.

1.0.1

  • Improve compatibility with other plugins by using more specific class and only adding it for JS fallback.
  • Run lazy-load script on DOMContentLoaded when necessary to improve compatibility with plugins like Autoptimize.
  • Do not transform elements inside an AJAX response due to lack of predictability of the context and script execution.

1.0.0

  • Initial release