Add controls for WP 6.3’s new asynch & defer attributes

Any chance you can implement these in a future release?

WordPress 6.3 introduces support for registering scripts with async and deferattributes as part of an enhancement to core’s existing Scripts API. This addresses a long-standing Trac ticket, and adds the ability to define a loading strategy for scripts. Supported strategies are as follows:

  • Blocking (default, this strategy is not supplied)
  • Deferred (by supplying a defer loading strategy)
  • Asynchronous (by supplying an async loading strategy)

This enhancement was originally proposed in December 2022.


+1 on this one. This would greatly improve performance for me.


On this topic, also support for inline & external module scripts. Just sharing the below, to see if anyone tried something similar, and have any suggestions.

Probably there are better solutions… meanwhile, pg-wp-addon, if it sets the information that the script is of type=“module” (can be extended to async, defer, once, nonce etc) in the script’s id (which currently is of format inline-script-x), then the id can be used by wp_inline_script_attributes && wp_script_attributes hooks to set the script tag as type="module".

For eg, (assuming assets are available within the public folder of the theme),

Flavour-1 - Module script imported using src

<script type="module" src="/assets/my-module.js"></script>

If this is generated…

wp_register_script('inline-module-script-1', "/assets/my-module.js", [], '1.0.0', true);
wp_scripts()->add_data('inline-module-script-1', 'type', 'module');

Flavour-2 - Module script where the import is within the script body (alternative to flavour-1)

<script type="module">
    import {something} from "/assets/my-module.js";

If this is generated…

wp_register_script('inline-module-script-1', '', [], '1.0.0', true);
wp_add_inline_script('inline-module-script-1', 'import {something} from "/assets/my-module.js";something();');

Then, we could use these two hooks to set the type="module" attribute like this (added to inc/custom.php):

Use this file to add custom PHP code to your theme or plugin 
add_filter('wp_inline_script_attributes', 'add_type_module_attribute');
add_filter('wp_script_attributes', 'add_type_module_attribute');
function add_type_module_attribute($attributes)
  if (isset($attributes['id']) && str_contains($attributes['id'], '-module')) {
    $attributes = array_merge($attributes, array('type' => 'module'));
  return $attributes;

Some related info, for any solution involving wp_scripts()->add_data('inline-script-1', 'type', 'module'); which probably won’t work for inline scripts