[wp-trac] [WordPress Trac] #12009: Add support for HTML 5 "async" and "defer" attributes

[WordPress Trac]

#12009: Add support for HTML 5 "async" and "defer" attributes
---------------------------+-----------------------------
 Reporter:  Otto42         |       Owner:  azaozz
     Type:  enhancement    |      Status:  reopened
 Priority:  normal         |   Milestone:  Future Release
Component:  Script Loader  |     Version:  4.6
 Severity:  normal         |  Resolution:
 Keywords:                 |     Focuses:
---------------------------+-----------------------------

Comment (by westonruter):

 @ocean90 here's a(nother) plugin implementation (and polyfill) for what
 you describe:

 {{{#!php
 <?php
 /**
  * Add async/defer attributes to enqueued scripts that have the specified
 script_execution flag.
  *
  * @link https://core.trac.wordpress.org/ticket/12009
  * @param string $tag    The script tag.
  * @param string $handle The script handle.
  * @return string
  */
 function wp12009_filter_script_loader_tag( $tag, $handle ) {
         $script_execution = wp_scripts()->get_data( $handle,
 'script_execution' );
         if ( ! $script_execution ) {
                 return $tag;
         }
         if ( 'async' !== $script_execution && 'defer' !==
 $script_execution ) {
                 return $tag; // _doing_it_wrong()?
         }

         // Abort adding async/defer for scripts that have this script as a
 dependency. _doing_it_wrong()?
         foreach ( wp_scripts()->registered as $script ) {
                 if ( in_array( $handle, $script->deps, true ) ) {
                         return $tag;
                 }
         }

         // Add the attribute if it hasn't already been added.
         if ( ! preg_match( ":\s$script_execution(=|>|\s):", $tag ) ) {
                 $tag = preg_replace( ':(?=></script>):', "
 $script_execution", $tag, 1 );
         }

         return $tag;
 }
 add_filter( 'script_loader_tag', 'wp12009_filter_script_loader_tag', 10, 2
 );
 }}}

 Then to make `comment-reply.js` async all that is needed is as you showed
 and @georgestephanis suggested:

 {{{#!php
 <?php
 add_action( 'wp_enqueue_scripts', function() {
         wp_script_add_data( 'comment-reply', 'script_execution', 'async'
 );
 } );
 }}}

 I like not using a boolean attribute, but the `script_execution` name
 doesn't feel quite right yet.

--
Ticket URL: <https://core.trac.wordpress.org/ticket/12009#comment:57>
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