Lazy Loader

Contributors: FlorianBrinkmann
Donate link: https://www.paypal.me/flobrinkmann
Tags: lazysizes, lazy loading, performance, images
Requires at least: 4.9.8
Tested up to: 6.5
Stable tag: 8.2.0
Requires PHP: 7.0

Description

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.
• Inline background images.
• Or all images and other enabled media in the markup (that is not excluded or already has a lazy loading attribute), via the option to process the complete markup.
• 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 (you can use the class skip-lazy by default).
• Add filters that should be processed by Lazy Loader.
• Enable lazy loading for iFrames.
• Include the lazysizes native loading plugin that modifies images and iFrames to use the native lazy loading feature of browsers that already support it.
• 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.
• Enable lazy loading for inline background images.
• 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).
• Process the complete markup of the site.
• A textarea to modify the default lazysizes config values.

* 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 not inserted with inline styles.
• Scripts.
• Styles.

The plugin adds a noscript element as fallback for disabled JavaScript (can be disabled with the lazy_loader_generate_noscript filter).

You can disable lazy loading for elements with specific CSS classes by defining them via the plugin settings (Settings › Media › Lazy Loader options). Or use the skip-lazy class or the data-skip-lazy attribute. skip-lazy and data-skip-lazy also work on wrapper elements to exclude the wrapper and its children from being processed.

Installation

• Install plugin.
• Activate it.
• You can find the plugin settings under Settings › Media › Lazy 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:

global $lazy_loader;
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 do that like in the following code block (remember to include the opening and closing style tags for additions/replacements). The code modifies the duration of the fade-in-effect:

add_filter( 'lazy_load_responsive_images_inline_styles', function ( $default_styles ) {
	$default_styles = sprintf(
		'%s <style>:root {
	--lazy-loader-animation-duration: 600ms;
}</style>',
		$default_styles
	);
	
	return $default_styles;
} );

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/other lazysizes settings?

There is a textarea in the plugin settings where you can insert custom settings for the lazysizes config.

Changelog

8.2.0 – 14.04.2024

Added

• lazy_loader_generate_noscript filter to allow disabling of noscript element generation.

Tested with WordPress 6.5.

Fixed

• Updated mastermind/html5 dependency to latest version, which fixes a PHP deprecation notice.

8.1.1 – 20.12.2022

Tested with WordPress 6.1.

Fixed

• Disable lazy loading in TranslatePress editor.

8.1.0 – 29.03.2021

Added

• Support for input elements of type image.

8.0.0 – 22.03.2021

Removed

• Processing of wp_get_attachment_image, introduced in 7.2.0. I just noticed that processing that filter by default may break cases where a wrapper element has the skip-lazy class to disable lazy loading for contained media elements. Lazy Loader is not aware of this when processing wp_get_attachment_image, because it cannot check the parent elements. If you want to process that filter with Lazy Loader, you can enter it in the settings field for additional filters.

7.2.3 – 19.03.2021

Fixed

• Stop processing embeds, because the lazysizes script is not loaded in the iframe and so the image in the embed can not be lazy loaded.

7.2.2 – 17.03.2021

Fixed

• Duplicate images in Ultimate Addons for Elementor widget – thanks @kagg-design.

7.2.1 – 09.03.2021 =

Fixed

• Missing JS files in SVN repo.

7.2.0 – 08.03.2021

Tested with WordPress 5.7.

Added

• Process wp_get_attachment_image filter that was added in WordPress 5.6.

Changed

• Updated lazysizes and its plugins to 5.3.0.

Fixed

• Use same escaped version of SVG placeholder for src and srcset to fix a HTML validation error.

7.1.0 – 04.11.2020

Changed

• Add timestamp of file modification as version query string to Lazy Loader JS files instead of WordPress version.

Fixed

• Problem with Lazy Loader being active in Oxygen Builder editor.

7.0.0 – 10.08.2020

If you depend on the aspectratio script of lazysizes somehow that came with the plugin, this release has a breaking change: it removes the aspectratio option (and the script) because it uses inline SVGs as placeholders that have the same effect without needing the aspectratio script.

Added

• Disable core lazy load funcionality that comes with WP 5.5.
• lazy_loader_attrs_to_strip_from_fallback_elem filter that allows to provide an array of HTML attributes that should be stripped from the fallback element in the noscript element.

Changed

• If width and height attributes are present, the plugin uses an inline SVG to prevent content reflow – thanks to WP.org user lozula.
• Updated lazysizes and its extensions to version 5.2.2.

Fixed

• Problems with inline HTML comments in script tags. To fix that. inline script elements are no longer wrapped in HTML comments during markup processing to hide them from the parser. That was necessary for DOMDocument() but is not needed when using Masterminds\HTML5() (what Lazy Loader does).

Removed

• Aspectratio option. The change with the inline SVG makes that obsolete.

6.0.1 – 01.05.2020

Changed

• Added empty default value for the $content param of Plugin\filter_markup() method to prevent a fatal error that occurs sometimes when Lazy Loader is used with the Content Cards plugin.
• Check if there is already a script with the lazysizes handle registered and deregister it before enqueuing own version. Fixes issue with Avada theme that includes own version.

6.0.0 – 31.01.2020

This release requires PHP 7

Added

• Option to process the complete markup of a page instead of only parts of it via the filters (might take a little longer because the plugin needs to process more markup and, if your site contains HTML errors, lead to unwanted behavior, because the DOM Parser tries to correct that).
• Option to define additional filters for the plugin to process.
• Ignore patterns for skip-lazy class and data-skip-lazy attribute. Use them if you want Lazy Loader to ignore an element and its children. The disable-lazyload class and data-no-lazyload attribute will keep working for backwards compatibility. Adding the new class and attribute goes back to an initiative by Frank Goossens, developer of Autoptimize, who reached out to several devs of lazy loading plugins or plugins that also have a lazy loading feature to get a standard class and attribute across multiple plugins.
• Added donation link to plugin header.

Changed

• Updated required PHP version to 7.0.
• Security improvements via escaping and specifying allowed HTML in setting descriptions. Thanks @igmoweb
• Simplified Plugin\add_noscript_element() method. It just clones the source element now, instead of creating a new empty element and adding all attributes to it.
• Check markup for [caption] shortcode to prevent duplicated images in Elementor.
• Class properties are private now.

Fixed

• Error with invalid attribute names in Plugin\add_noscript_element() method.

5.1.2 – 12.11.2019

Changed

• Updated background image option text.

5.1.1 – 11.11.2019

Changed

• Updated readme.

5.1.0 – 11.11.2019

Added

• Lazy loading of background images.
• Lazy loading of videos with autoplay.

Changed

• Updated lazysizes and its extensions to 5.1.2.
• Updated tested up to version to 5.3.

Fixed

• Handle rest api requests with edit context as admin requests (thanks @websupporter!).
• Check if a post type supports custom-fields before loading block editor script.

5.0.0 – 28.06.2019

Changed

• Increased priority for the calls of the_content and post_thumbnail_html filters from 500 to 10001 to fix issues with the ShortPixel Image Optimizer. So if you use those filters and they need to run after the Lazy Loader, you need to increase the priority, too. This is the change that makes it a major version change.

Fixed

• Audio shortcode stripped from frontend with all following content.

4.1.0 – 31.05.2019

Tested with WordPress 5.2

Added

• Option for using the native loading extension from lazysizes.
• Textarea for custom lazysizes config values.

Changed

• Updated lazysizes to 5.1.0.
• Use CSS variable var(--lazy-loader-animation-duration) for duration of fade-in-effect after loading.

Fixed

• Do not load assets on pages where Lazy Loader is disabled.
• Preserve HTML and hex entities.
• Ignore inline scripts.
• Skip images that already have a data-src attribute.
• Checkbox for disabling Lazy Loader not showing for Custom Post Types added via a plugin.

4.0.1 – 20.02.2019

Fixed

• Removed debug code.

4.0.0 – 20.02.2019

Tested with WordPress 5.1.

Changed

• 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.

Fixed

• 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

Fixed

• Wrong version number in plugin file.

3.5.0 – 28.01.2019

Added

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

Changed

• 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).

Fixed

• 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

Added

• Support for picture element.

Fixed

• 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

Fixed

• Disable libxml errors.

3.3.6 – 11.06.2018

Changed

• 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.

Fixed

• Fix encoding issues with strings inside script elements.

3.3.5 – 14.04.2018

Fixed

• Not working with PHP 5.3.

3.3.4 – 05.04.2018

Fixed

• 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.

Changed

• 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

Fixed

• 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

Fixed

• 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

Fixed

• 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…)

Added

• 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.

Changed

• 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.

Fixed

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

3.2.10 – 06.03.2018

Fixed

• Small error in the readme.

3.2.9 – 06.03.2018

Added

• 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 W.org user zitrusblau for the hint with the plugin.

3.2.8 – 27.02.2018

Fixed

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

3.2.7 – 22.02.2018

Added

• Animated the opacity change when the images are loaded.

Fixed

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

3.2.6 – 30.11.2017

Changed

• 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

Fixed

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

3.2.4 – 25.11.2017

Fixed

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

3.2.3 – 25.11.2017

Fixed

• Line break issues with the readme for W.org.

3.2.2 – 25.11.2017

Fixed

• Problem with duplicated images in HTML widget.

3.2.1 – 25.11.2017

Fixed

• Load minified version of lazysizes unveilhooks plugin.

3.2.0 – 25.11.2017

Added

• 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

• 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.

Fixed

• Small doc errors.

3.1.13 – 08.11.2017

Changed

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

3.1.12 – 22.09.2017

Fixed

• 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

Changed

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

Fixed

• Now also adds a noscript element for gallery images.

Removed

• 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

Fixed

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

3.1.9 – 25.08.2017

Fixed

• Product image appears twice in WooCommerce cart.

3.1.8 – 10.08.2017

Fixed

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

3.1.7 – 10.08.2017

Fixed

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

3.1.6 – 07.08.2017

Fixed

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

3.1.5 – 20.07.2017

Fixed

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

3.1.4 – 14.07.2017

Fixed

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

3.1.3 – 07.07.2017

Fixed

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

3.1.2

Fixed

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

3.1.1

Changed

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

Fixed

• Correct text domain.

3.1.0

Added

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

Changed

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

3.0

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

1.0.9

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

1.0.8

• Bugfix for missing images if javascript is disabled.

1.0.7

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

1.0.6

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

1.0.5

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

1.0.4

• 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.

1.0.3

• fixed path to js and css.

1.0.2

• typo in WordPress usernames.

Thanks

Thanks to @mtoensing who created a W.org plugin from the code described in one of my posts and maintained it for the first 1,5 years.

And thanks to all contributors who helped with Pull Requests and/or opened Issues.