Avoid error in deferred scripts.

.gitattributes

@@ -4,3 +4,4 @@
 .wp-env.json export-ignore
 assets-lazy-loader.php export-ignore
 package.json export-ignore
+test.js export-ignore

README.md

@@ -45,6 +45,16 @@ Kunoichi\AssetsLazyLoader\ScriptsDefer::enable( [
 ] );
 ```
 
+Some JavaScripts have following scripts via `wp_add_inline_script`. This may cause critical erros. `ScriptDefer` skips enqueued scripts with `after` section, but for more safety, consider allow list approach.
+
+```php
+Kunoichi\AssetsLazyLoader\ScriptsDefer::enable( [
+	// Defer scripts only which you know they are safe with defer attribute.
+	'exclude'  => [ 'your-js', 'jquery' ], 
+] );
+```
+
+
 ### CSS Preload
 
 Add `rel="preload"` to `link` tag and fallback scripts.

assets-lazy-loader.php

@@ -31,7 +31,7 @@
 
 // Enqueue jQuery
 add_action( 'wp_enqueue_scripts', function() {
-	wp_enqueue_script( 'jquery' );
+	wp_enqueue_script( 'assets-lazy-loader', plugins_url( 'test.js', __FILE__ ), [ 'jquery', 'wp-api-fetch' ], '1.0.0' );
 } );
 
 // Defer JS

src/Kunoichi/AssetsLazyLoader/Pattern/HandleDetector.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace Kunoichi\AssetsLazyLoader\Pattern;
+
+/**
+ * Handle detector
+ *
+ * @package assets-lazy-loader
+ * @property-read string[] $exclude
+ * @property-read string[] $include
+ */
+abstract class HandleDetector extends Singleton {
+
+	/**
+	 * Add extra arguments.
+	 *
+	 * @param array $args
+	 * @return array
+	 */
+	protected function parse_args( $args ) {
+		return array_merge( [
+			'exclude' => [],
+			'include' => [],
+		], parent::parse_args( $args ) );
+	}
+
+	/**
+	 * Check if handle is avilable.
+	 *
+	 * @param string $handle
+	 * @return bool
+	 */
+	protected function is_valid_handle( $handle ) {
+		if ( ( ! $this->in_admin ) && is_admin() ) {
+			// If not in admin, skip.
+			return false;
+		}
+		if ( ( ! $this->in_login ) && $this->is_login() ) {
+			// If not in login, skip.
+			return false;
+		}
+		if ( $this->include ) {
+			// Allow list exists, check if it's included.
+			return in_array( $handle, (array) $this->include, true );
+		} elseif ( $this->exclude ) {
+			// Deny list exists, check if it's included.
+			return ! in_array( $handle, (array) $this->exclude, true );
+		} else {
+			return true;
+		}
+	}
+
+}

src/Kunoichi/AssetsLazyLoader/ScriptsDefer.php

@@ -3,28 +3,19 @@
 namespace Kunoichi\AssetsLazyLoader;
 
 
-use Kunoichi\AssetsLazyLoader\Pattern\Singleton;
+use Kunoichi\AssetsLazyLoader\Pattern\HandleDetector;
 
 /**
  * Defer JavaScripts
  *
  * @package assets-lazy-loader
- * @property-read string[] $exclude
  */
-class ScriptsDefer extends Singleton {
+class ScriptsDefer extends HandleDetector {
 
 	/**
-	 * Override parser
-	 *
-	 * @param array $args
-	 *
-	 * @return array
+	 * @var string[] Critical scripts not to be deferred.
 	 */
-	protected function parse_args( $args ) {
-		return array_merge( [
-			'exclude' => [],
-		], parent::parse_args( $args ) );
-	}
+	protected $critical_scripts = [ 'wp-i18n' ];
 
 	/**
 	 * Register filter hooks.
@@ -36,14 +27,6 @@ protected function init() {
 				define( 'CONCATENATE_SCRIPTS', false );
 			}
 		}
-		if ( ! $this->in_admin && is_admin() ) {
-			// This is admin and not in admin.
-			return;
-		}
-		if ( ! $this->in_login && $this->is_login() ) {
-			// This is login screen and not in login.
-			return;
-		}
 		// Filter script loader.
 		add_filter( 'script_loader_tag', [ $this, 'script_loader_tag' ], 9999, 2 );
 	}
@@ -56,8 +39,7 @@ protected function init() {
 	 * @return string
 	 */
 	public function script_loader_tag( $tag, $handle ) {
-		// If this is excluded tag, skip.
-		if ( in_array( $handle, (array) $this->exclude, true ) ) {
+		if ( ! $this->is_valid_handle( $handle ) ) {
 			return $tag;
 		}
 		// Already having "defer" or "async", skip.
@@ -66,7 +48,33 @@ public function script_loader_tag( $tag, $handle ) {
 				return $tag;
 			}
 		}
+		// If critical, skip.
+		if ( in_array( $handle, $this->critical_scripts, true ) ) {
+			return $tag;
+		}
+		// Having after script, skip.
+		if ( $this->has_after( $handle ) ) {
+			return $tag;
+		}
 		// Add defer.
 		return str_replace( ' src=', ' defer src=', $tag );
 	}
+
+	/**
+	 * If after script, skip.
+	 *
+	 * @param string $handle
+	 * @return bool
+	 */
+	protected function has_after( $handle ) {
+		global $wp_scripts;
+		if ( ! isset( $wp_scripts->registered[ $handle ] ) ) {
+			return false;
+		}
+		$script = $wp_scripts->registered[ $handle ];
+		if ( ! empty( $script->extra['after'] ) ) {
+			return true;
+		}
+		return false;
+	}
 }

src/Kunoichi/AssetsLazyLoader/StyleLoader.php

@@ -3,15 +3,14 @@
 namespace Kunoichi\AssetsLazyLoader;
 
 
-use Kunoichi\AssetsLazyLoader\Pattern\Singleton;
+use Kunoichi\AssetsLazyLoader\Pattern\HandleDetector;
 
 /**
  * Style loader.
  *
  * @package assets-lazy-loader
- * @property-read string[] $exclude
  */
-class StyleLoader extends Singleton {
+class StyleLoader extends HandleDetector {
 
 	/**
 	 * @var bool If set preload at least 1, enable.
@@ -28,18 +27,6 @@ public static function admin_critical( $extra = [] ) {
 		return array_merge( [ 'login', 'common', 'admin-bar', 'admin-menu', 'dashboard' ], $extra );
 	}
 
-	/**
-	 * Add extra arguments.
-	 *
-	 * @param array $args
-	 * @return array
-	 */
-	protected function parse_args( $args ) {
-		return array_merge( [
-			'exclude' => [],
-		], parent::parse_args( $args ) );
-	}
-
 	/**
 	 * Constructor.
 	 */
@@ -77,15 +64,7 @@ public function preload_helper() {
 	 * @return string
 	 */
 	public function style_loader_tag( $tag, $handle, $href, $media ) {
-		if ( ( ! $this->in_admin ) && is_admin() ) {
-			// If not in admin, skip.
-			return $tag;
-		}
-		if ( ( ! $this->in_login ) && $this->is_login() ) {
-			// If not in login, skip.
-			return $tag;
-		}
-		if ( in_array( $handle, (array) $this->exclude, true ) ) {
+		if ( ! $this->is_valid_handle( $handle ) ) {
 			return $tag;
 		}
 		// If already preload or print, skip.

test.js

@@ -0,0 +1,5 @@
+/*!
+ * Description
+ */
+
+console.log( 'Assets Lazy Loader' );