[wp-trac] [WordPress Trac] #53675: Omit lazy-loading attribute on first content image/iframe

[WordPress Trac]

#53675: Omit lazy-loading attribute on first content image/iframe
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 Reporter:  flixos90                      |       Owner:  flixos90
     Type:  enhancement                   |      Status:  assigned
 Priority:  normal                        |   Milestone:  5.9
Component:  Media                         |     Version:  5.5
 Severity:  normal                        |  Resolution:
 Keywords:  needs-patch needs-unit-tests  |     Focuses:  performance
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Comment (by westonruter):

 Replying to [comment:3 flixos90]:
 > @westonruter This is close to what I did in the prototype plugin used
 for the analysis - the one thing missing from yours (as you mention in the
 other ticket) was archive support. It would be great if you could review
 the prototype plugin (see below) and leave your thoughts.

 Actually, my plugin does account for the archive template. My comment was
 referring to how twentytwentyone was not omitting `loading=lazy` from the
 first post's featured image on an archive template.

 In your POC, you're stripping out `loading="lazy"` from the HTML of the
 featured image.  Would it not be better to rather filter
 `wp_lazy_loading_enabled`? See
 [https://gist.github.com/westonruter/e8d5778843005b7e0d6ce4049b3ec29d
 #file-prevent-lazy-loading-primary-featured-image-php-L75 alternative].

 It's good how you're using `wp_img_tag_add_loading_attr` to account for
 markup in the content beyond just the featured image.

 What if someone is adding an image to the template outside of
 `the_content()` and `the_post_thumbnail()`? They could also obtain an
 image via `wp_get_attachment_image()` directly. Since that function
 applies the `wp_lazy_loading_enabled` filter, perhaps the filter should
 increment the counter instead of in the `post_thumbnail_html` and
 `wp_img_tag_add_loading_attr` filters both?

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Ticket URL: <https://core.trac.wordpress.org/ticket/53675#comment:6>
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