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WordPress plugin for lazy loading images. Works with responsive images and uses lazysizes.
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Lazy Loader

Contributors: FlorianBrinkmann, MarcDK
Tags: lazysizes, lazy loading, performance, images
Requires at least: 4.5
Tested up to: 5.1
Stable tag: 4.0.1
Requires PHP: 5.3


Lazy loading plugin that supports images, iFrames, video and audio elements and uses the lightweight lazysizes script. With manual modification of the markup it is also possible to lazy load background images, scripts, and styles.

Lazy loads (without the need of any manually modifications):

  • Images inserted via img or picture in posts, pages, Custom Post Types, Text Widgets, …
  • Post thumbnails.
  • iFrames.*
  • Video elements.*
  • Audio elements.*

* Can be enabled in the plugin options.

The plugin comes with the following options (under Settings › Media › Lazy Loader options):

  • Do not lazy load elements with specific CSS classes.
  • Enable lazy loading for iFrames.
  • Include the lazysizes unveilhooks plugin that adds support for more elements, for example, video and audio elements.*
  • Enable lazy loading for the poster frame of video elements.
  • Enable lazy loading for audio elements.
  • Include lazysizes aspectratio plugin. This plugin calculates the needed space for images before they are loaded. That avoids content jumping when the images are loaded and makes the lazy loading work with masonry grids.
  • Display a loading spinner.
  • Disable the plugin on specific posts/pages (this shows a checkbox in the edit view of all public post types (except attachments) to disable lazy loading for an entire post).

* The unveilhooks extension of lazysizes supports more than video and audio elements, but you need to manually modify the markup to use it for:

  • Background images.
  • Scripts.
  • Styles.

The plugin adds a noscript element as fallback for disabled JavaScript.

The auto-modifying of the image markup does not work for images that are added using wp_get_attachment_image(), because there cannot be a noscript fallback added.

You can disable lazy loading for elements with specific CSS classes by defining them via the plugin settings (SettingsMediaLazy Loader options). Or use the data-no-lazyload attribute.

If you want to disable lazy loading for a specific element and its children (for example, if you have no access to the classes of the image element), you can use the disable-lazyload class.


  • Install plugin.
  • Activate it.
  • You can find the plugin settings under SettingsMediaLazy Loader options.

Frequently Asked Questions

Is there a way to manually call the plugin to modify markup of not-supported image functions?

Yes. See the following example that would generate lazy-load-ready output for the result of the not-supported wp_get_attachment_image() function:

if ( isset( $lazy_loader ) && $lazy_loader instanceof FlorianBrinkmann\LazyLoadResponsiveImages\Plugin ) { echo $lazy_loader->filter_markup( wp_get_attachment_image( 1261 ) ); }

To make it happen, you need to pass the markup that contains the image (or images) to $lazy_loader->filter_markup(). The if statement ensures that the Lazy Loader object is there and that it is an object of the correct class.

How can I disable/modify the inline styles?

Important: If you modify or remove the inline styles, also the style that shows the loading spinner is affected. So if you remove the styles or modify them without adding back the spinner styles, the spinner option will not work. I created a Gist with the spinner styles – just add them to your modification to make it work.

To disable or modify the plugin’s inline styles (except the style that hides the img.lazyload elements when JS is disabled, so only the noscript version is displayed) you can use the lazy_load_responsive_images_inline_styles filter. For example, to remove the inline styles, use the following code:

add_filter( 'lazy_load_responsive_images_inline_styles', function () { return ''; } );

If you want to modify it, you can overwrite the plugin’s styles like that (remember to include the opening and closing style tags):

` add_filter( 'lazy_load_responsive_images_inline_styles', function ( $default_styles ) { return '<style>.lazyload { display: block; }

	.lazyloading {
		opacity: 0;

	.lazyloaded {
		opacity: 1;
		transition: opacity 300ms;

} ); `

The CSS from the example are the default styles that are used by the plugin (without the loading spinner styles). The display: block for .lazyload is important for the aspectratio plugin option.

How can I adjust the lazy load threshold?

I described that in a support forum post.


4.0.1 – 20.02.2019


  • Removed debug code.

4.0.0 – 20.02.2019

Tested with WordPress 5.1.


  • Renamed object in main plugin file from $plugin to $lazy_loader to make it accessible via the theme.
  • Added an example for calling the filter_markup() method of the plugin from the theme to modify markup of not-supported image functions like wp_get_attachment_image().
  • Updated lazysizes to 4.1.6.


  • Wrong year in changelog for 3.5.0 and 3.5.1. Thanks @pra85!
  • Correctly remove the plugin options from the options database table on uninstall.

3.5.1 – 28.01.2019


  • Wrong version number in plugin file.

3.5.0 – 28.01.2019


  • Option to disable lazy loading for specific posts/pages via a checkbox. The checkbox can be enabled via an option under SettingsMediaLazy Loader options.
  • Possibility to use the disable-lazyload class to disable the lazy loader for an element and its children.


  • Updated lazysizes to 4.1.5.
  • Added note about limited browser support to loading spinner option.
  • Updated placeholder source to a more stable variation (thanks diegocanal for the hint).


  • Only use save_html() method if markup was modified.
  • Keep srcset attribute with placeholder source to get valid HTML.

3.4.0 – 05.07.2018


  • Support for picture element.


  • Only use data-sizes attribute, if value is auto.
  • Removed unnecessary check for src attribute in modify_img_markup().

3.3.7 – 12.06.2018


  • Disable libxml errors.

3.3.6 – 11.06.2018


  • Set a transparent data URI as img src instead of removing it to avoid page jumps that can happen during image loading (at least in Chrome).
  • Updated lazysizes and plugins to 4.0.4.


  • Fix encoding issues with strings inside script elements.

3.3.5 – 14.04.2018


  • Not working with PHP 5.3.

3.3.4 – 05.04.2018


  • Use correct pattern for lazy loading of video and audio elements.
  • Removed unnecessary else and a chunk of duplicate code (thanks mackzwellz).
  • Issue with encoding of cyrillic characters.


  • Updated lazysizes.js and the bundled plugins to 4.0.2.
  • Run post_thumbnail_html filter later (priority 500, like for the the_content filter call, instead of 10), to fix a problem that appears when used with Responsify WP (thanks jgadbois).
  • Moved the add_noscript_element() method call to the beginning of the modify_*_markup methods. With that, there is no need to remove the lazyload class in the add_noscript_element() method, because it was not added yet.
  • Removed unnecessary $new_iframe->setAttribute( 'src', $src ) call from the add_noscript_element().
  • Removed unnecessary $dom->saveHTMLExact() calls from the modify_*_markup methods.
  • Use own FlorianBrinkmann\LazyLoadResponsiveImages\Helpers()->save_html() method for saving the HTML.

3.3.3 – 13.03.2018


  • Fix broken code blocks in readme file.
  • Set .lazyload to display: block to make the aspectratio option work correctly again.

3.3.2 – 09.03.2018


  • Removed try to get width and height from images without width and height attr with getimagesize because it may cause a PHP warning.

3.3.1 – 09.03.2018


  • Added inline doc for FlorianBrinkmann\LazyLoadResponsiveImages\Settings()->add_color_picker().
  • Only load color picker styles and script if on media settings page.

3.3.0 – 09.03.2018

(there was also a new feature added in 3.2.9, but I forgot to increase the minor version number there…)


  • lazy_load_responsive_images_inline_styles filter for modifying the inline CSS (for modification, you also need to add the opening and closing style tags). If you use the spinner option and the filter, you need to add the spinner styles, because they are part of the filtered CSS (Gist with the spinner styles used by default).
  • Option to display a loading spinner and define its color.


  • Use style inside noscript element to hide .lazyload images if no JS instead of adding a js class via JS to the html element.
  • Using DOMXpath()->query() to fetch the element nodes.
  • Looping the nodes once inside FlorianBrinkmann\LazyLoadResponsiveImages\Plugin()->filter_markup() and no longer one time in each of the three element-specific methods.


  • Do not modify elements inside noscript elements.
  • Doc fixes.

3.2.10 – 06.03.2018


  • Small error in the readme.

3.2.9 – 06.03.2018


  • Option to load the lazysizes aspectratio plugin. This plugin calculates the space that the images need before they are loaded. With that enabled, the lazy loading should also work for masonry grids without further markup modifications. Thanks to user zitrusblau for the hint with the plugin.

3.2.8 – 27.02.2018


  • Correctly set .lazyload images to display: none if JS is disabled.

3.2.7 – 22.02.2018


  • Animated the opacity change when the images are loaded.


  • Duplicated images if, for example, the the_content filter is run multiple times.
  • Small doc fix.

3.2.6 – 30.11.2017


  • Automatically load unveilhooks extension if audio or video option is enabled, regardless of the option to load the unveilhooks plugin is enabled or not.
  • Updated Tested up to version to 4.9.1.

3.2.5 – 27.11.2017


  • Wrong path to plugin options in the readme.txt.

3.2.4 – 25.11.2017


  • Fatal error due case mismatch in referencing the SmartDOMDocument class – sorry for that!

3.2.3 – 25.11.2017


  • Line break issues with the readme for

3.2.2 – 25.11.2017


  • Problem with duplicated images in HTML widget.

3.2.1 – 25.11.2017


  • Load minified version of lazysizes unveilhooks plugin.

3.2.0 – 25.11.2017


  • Option to automatically lazy load iFrames.
  • Option to automatically lazy load videos.
  • Option to automatically lazy load audio.
  • Option to additionally load the unveilhooks plugin of lazysizes. This enables lazy loading of audio, video, scripts, and more.
  • Support for images inside the text and HTML widget. Does not work for galleries in the widgets.
  • Support for Gravatars.
  • Autoloading of classes with Composer.


  • Changed plugin name to »Lazy Loader«.
  • Moved settings to the media settings page and removed the customizer section.
  • PHP comment style for inline comments.
  • Renamed the class files in src.


  • Small doc errors.

3.1.13 – 08.11.2017


  • Updated lazysizes to 4.0.1.
  • Updated »Tested up to« version to 4.9 in readme.

3.1.12 – 22.09.2017


  • Added back the support for data-no-lazyload attr to disable lazy loading for specific images (was removed in 3.1.0 without keeping backwards compatibility in mind, sorry).

3.1.11 – 19.09.2017


  • Added details to the readme, what images are lazy loaded.


  • Now also adds a noscript element for gallery images.


  • No lazy loading for images that are added via wp_get_attachment_image(), because for those images cannot be added a noscript fallback.

3.1.10 – 17.09.2017


  • is_admin_request() check does not work for subdirectory installs.

3.1.9 – 25.08.2017


  • Product image appears twice in WooCommerce cart.

3.1.8 – 10.08.2017


  • Bump »Requires at least« to 4.5 because using wp_add_inline_script() since a few versions.

3.1.7 – 10.08.2017


  • Use saveHTMLExact() method from SmartDomDocument to prevent doctype, html and body element to be added to the content.

3.1.6 – 07.08.2017


  • Disable lazy loading for AMP pages which are generated by the »AMP« plugin by Automattic.

3.1.5 – 20.07.2017


  • Further issues with PHP 5.3.
  • Issue with lazy loaded post thumbnail in the backend.

3.1.4 – 14.07.2017


  • Replaced [] array syntax with traditional one, so it works with PHP 5.3 again.

3.1.3 – 07.07.2017


  • Wrong check for js class, which causes hidden images if nothing else added a js class…



  • Capital P for one »WordPress« in readme and one in plugin description.



  • Added option to disable lazy loading for specific classes to readme.


  • Correct text domain.



  • Customizer option to specify image class names to disable lazy loading for those.


  • Using semver.
  • Make it work with AJAX requests (thanks to zitrusblau).
  • Using classes and namespaces.
  • Using SmartDomDocument class.
  • Updated plugin URL.
  • Doc improvements.


  • Updated lazysizes to 3.0.0 (Thanks FlorianBrinkmann)
  • Plugin version reflects version of lazysizes.


  • Allow opting out of lazy load with "data-no-lazyload" attribute (Thanx wheresrhys)


  • Bugfix for missing images if javascript is disabled.


  • Added a check to prevent the plugin being applied multiple times on the same image. (Thanx to saxonycreative)


  • added missing src attribute. Older browsers like the PS4 browser now work again.


  • now prevents lazy loading in atom feeds and the WordPress backend.


  • Changed description to reflect the compatibility with WordPress 4.4 core responsive images.
  • Removed skipping of the first image in the post.
  • Adds css class "js" to body tag for better compatibility.


  • fixed path to js and css.


  • typo in WordPress usernames.
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