[wp-trac] [WordPress Trac] #58211: Conditionally skip lazy-loading on images before the loop in classic themes

[WordPress Trac]

#58211: Conditionally skip lazy-loading on images before the loop in classic themes
--------------------------+------------------------------------------
 Reporter:  flixos90      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  6.3
Component:  Media         |    Version:  5.9
 Severity:  normal        |   Keywords:  needs-patch needs-unit-tests
  Focuses:  performance   |
--------------------------+------------------------------------------
 [55318] includes an enhancement which for block themes avoids lazy-loading
 images that appear in the `header` block template part. While that
 resolves a common performance problem with lazy-loaded images in the
 header of a page for block themes, sites using a classic theme still run
 into this problem.

 Specifically, in classic themes today only images that are rendered while
 `in_the_loop()` are eligible to have lazy-loading skipped on them. This
 ticket aims to introduce conditions to make images eligible for skipping
 lazy-loading that are included ''before'' the loop.

 We can fix the problem by updating `wp_get_loading_attr_default()` to omit
 lazy-loading / return `false` if all of the following applies:
 * `$context` is either "the_post_thumbnail" or "wp_get_attachment_image"
 * the `get_header` action has already run
 * the main query loop has not started yet
 * the `get_footer` action has not yet run

 This effectively results in images in the header but before the main query
 loop to not be lazy-loaded. In cases where a special page template does
 not contain a query loop, the `get_footer` action acts as a "fallback" to
 ensure that footer images are still lazy-loaded.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/58211>
WordPress Trac <https://core.trac.wordpress.org/>
WordPress publishing platform