Enhance the admin asset API to cover loading strategy as well

admin/class-admin-asset-manager.php

@@ -88,14 +88,21 @@ public function enqueue_user_language_script() {
 	 * @return void
 	 */
 	public function register_script( WPSEO_Admin_Asset $script ) {
-		$url = $script->get_src() ? $this->get_url( $script, WPSEO_Admin_Asset::TYPE_JS ) : false;
+		$url  = $script->get_src() ? $this->get_url( $script, WPSEO_Admin_Asset::TYPE_JS ) : false;
+		$args = [
+			'in_footer' => $script->is_in_footer(),
+		];
+
+		if ( $script->get_strategy() !== '' ) {
+			$args['strategy'] = $script->get_strategy();
+		}
 
 		wp_register_script(
 			$this->prefix . $script->get_name(),
 			$url,
 			$script->get_deps(),
 			$script->get_version(),
-			$script->is_in_footer()
+			$args
 		);
 
 		if ( in_array( 'wp-i18n', $script->get_deps(), true ) ) {

admin/class-asset.php

@@ -121,6 +121,13 @@ class WPSEO_Admin_Asset {
 	 */
 	protected $in_footer;
 
+	/**
+	 * For JS Assets. The script's async/defer strategy.
+	 *
+	 * @var string
+	 */
+	protected $strategy;
+
 	/**
 	 * For CSS Assets. Whether this stylesheet is a right-to-left stylesheet.
 	 *
@@ -147,6 +154,7 @@ class WPSEO_Admin_Asset {
 		'media'     => 'all',
 		'version'   => '',
 		'suffix'    => '',
+		'strategy'  => '',
 	];
 
 	/**
@@ -173,6 +181,7 @@ public function __construct( array $args ) {
 		$this->version   = $args['version'];
 		$this->media     = $args['media'];
 		$this->in_footer = $args['in_footer'];
+		$this->strategy  = $args['strategy'];
 		$this->rtl       = $args['rtl'];
 		$this->suffix    = $args['suffix'];
 	}
@@ -235,6 +244,15 @@ public function is_in_footer() {
 		return $this->in_footer;
 	}
 
+	/**
+	 * Returns the script asset's async/defer loading strategy.
+	 *
+	 * @return string
+	 */
+	public function get_strategy() {
+		return $this->strategy;
+	}
+
 	/**
 	 * Returns whether this CSS has a RTL counterpart.
 	 *