1 files changed, 35 insertions, 0 deletions
diff --git a/app/assets/javascripts/content_editor/services/code_block_language_loader.js b/app/assets/javascripts/content_editor/services/code_block_language_loader.js
new file mode 100644
index 00000000000..3c12cf614a5
--- /dev/null
+++ b/app/assets/javascripts/content_editor/services/code_block_language_loader.js
@@ -0,0 +1,35 @@
+export default class CodeBlockLanguageLoader {
+  constructor(lowlight) {
+    this.lowlight = lowlight;
+  }
+
+  isLanguageLoaded(language) {
+    return this.lowlight.registered(language);
+  }
+
+  loadLanguagesFromDOM(domTree) {
+    const languages = [];
+
+    domTree.querySelectorAll('pre').forEach((preElement) => {
+      languages.push(preElement.getAttribute('lang'));
+    });
+
+    return this.loadLanguages(languages);
+  }
+
+  loadLanguages(languageList = []) {
+    const loaders = languageList
+      .filter((languageName) => !this.isLanguageLoaded(languageName))
+      .map((languageName) => {
+        return import(
+          /* webpackChunkName: 'highlight.language.js' */ `highlight.js/lib/languages/${languageName}`
+        )
+          .then(({ default: language }) => {
+            this.lowlight.registerLanguage(languageName, language);
+          })
+          .catch(() => false);
+      });
+
+    return Promise.all(loaders);
+  }
+}