#3382238: Dynamically register languages.

assets/js/init_highlightjs.js

-/**
- * @file
- * Enables syntax highlighting via HighlightJS.
- */
-
-(function (hljs) {
-  'use strict';
-  hljs.initHighlightingOnLoad();
-})(hljs);

highlightjs_input_filter.libraries.yml

 highlightjs:
   version: VERSION
   js:
-    //cdnjs.cloudflare.com/ajax/libs/highlight.js/11.7.0/highlight.min.js: { type: external, minified: true }
-    assets/js/init_highlightjs.js: { minified: false }
+    js/highlightjs_input_filter.js: {  attributes: { type: module }, minified: false }
   css:
     theme:
       //cdnjs.cloudflare.com/ajax/libs/highlight.js/11.7.0/styles/xcode.min.css: { type: external }

js/highlightjs_input_filter.js

+/**
+ * @file
+ * Enables syntax highlighting via HighlightJS.
+ */
+import hljs from 'https://unpkg.com/@highlightjs/cdn-assets@11.8.0/es/core.min.js';
+
+(function (Drupal, drupalSettings) {
+  const languages = drupalSettings.highlightJsLanguages || [];
+  const promises = languages.map(language => {
+    return import(`https://unpkg.com/@highlightjs/cdn-assets@11.8.0/es/languages/${language}.min.js`)
+      .then(module => hljs.registerLanguage(language, module.default));
+  });
+
+  Drupal.behaviors.highlightInit = {
+    attach () {
+      Promise.all(promises).then(() => {
+        hljs.highlightAll();
+      })
+    }
+  }
+})(Drupal, drupalSettings)

src/Plugin/Filter/HighlightJs.php

@@ -26,11 +26,23 @@ class HighlightJs extends FilterBase {
       return $result;
     }
 
+    $pattern = "/language-[^\"]+/i";
+    if (preg_match_all($pattern, $result, $matches)) {
+      foreach ($matches as $match) {
+        foreach ($match as $language_id) {
+          $languages[] = str_replace('language-', '', $language_id);
+        }
+      }
+    }
+
     // Add needed JS.
     $result->addAttachments([
       'library' => [
         'highlightjs_input_filter/highlightjs',
       ],
+      'drupalSettings' => [
+        'highlightJsLanguages' => array_unique($languages),
+      ],
     ]);
 
     return $result;