[wp-trac] [WordPress Trac] #59462: Blocks: Introduce a way to enqueue view scripts only when needed for interactivity

[WordPress Trac]

#59462: Blocks: Introduce a way to enqueue view scripts only when needed for
interactivity
-------------------------+----------------------
 Reporter:  gziolo       |      Owner:  (none)
     Type:  enhancement  |     Status:  assigned
 Priority:  normal       |  Milestone:  6.5
Component:  Editor       |    Version:  trunk
 Severity:  normal       |   Keywords:
  Focuses:               |
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 It's based on the discussion started by @felixarntz in
 https://github.com/WordPress/wordpress-
 develop/pull/5262#discussion_r1336258326 when reviewing the current
 handling for interactive blocks back ported from the Gutenberg plugin for
 WordPress 6.4 Beta 1.

 As of today, the view scripts get enqueued during block rendering in
 `WP_Block::render`:

 https://github.com/WordPress/wordpress-
 develop/blob/6a61084beca680a78ed581d035d76d592d4ef117/src/wp-includes
 /class-wp-block.php#L271-L274

 The custom code used with all core blocks applies the optimization by
 ensuring that these view scripts are only listed for enqueuing when the
 block instance of a given type is going to need them. For example, in the
 Image block, the view script is only useful when the Lightbox feature is
 activated for the block. There can be multiple block instances of the same
 type, so the view script gets removed from the list when the functionality
 isn't used. However, as soon as any block instance needs it, it must be
 added and never removed.

 The reason why we didn't go with `wp_enqueue_script()` and
 `wp_dequeue_script()` is that the script handle would still need to get
 removed from `view_script_handles` for the block type as it gets
 automatically registered through `block.json` and later enqueued in the
 code path shared in the snippet above. It would still have to be manually
 enqueued when it is needed.

 In the long run, I hope we can develop some sort of automatic detection
 based on Interactivity API directives that would inform whether a view
 script is necessary for the block. It could even allow us to introduce new
 strategies that allow loading scripts based on some triggers like: when a
 user hovers over a UI element or when the UI element is visible on the
 screen.

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Ticket URL: <https://core.trac.wordpress.org/ticket/59462>
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