1 files changed, 30 insertions, 0 deletions
diff --git a/packages/gitbook-plugin-highlight/src/getLanguage.js b/packages/gitbook-plugin-highlight/src/getLanguage.js
new file mode 100644
index 0000000..47b68cf
--- /dev/null
+++ b/packages/gitbook-plugin-highlight/src/getLanguage.js
@@ -0,0 +1,30 @@
+const GitBook = require('gitbook-core');
+const { List } = GitBook.Immutable;
+
+/**
+ * Return language for a code blocks from a list of class names
+ *
+ * @param {Array<String>}
+ * @return {String}
+ */
+function getLanguage(classNames) {
+    return List(classNames)
+        .map(function(cl) {
+            // Markdown
+            if (cl.search('lang-') === 0) {
+                return cl.slice('lang-'.length);
+            }
+
+            // Asciidoc
+            if (cl.search('language-') === 0) {
+                return cl.slice('language-'.length);
+            }
+
+            return null;
+        })
+        .find(function(cl) {
+            return Boolean(cl);
+        });
+}
+
+module.exports = getLanguage;