From eb231bf01aa8c2133427e2745b5f92a708af82ee Mon Sep 17 00:00:00 2001
From: Anton Wilhelm <timaschew@users.noreply.github.com>
Date: Thu, 12 Sep 2019 17:10:16 +0200
Subject: [PATCH] fix($theme-default): Expand nested sidebar groups (#1540)

---
 .../theme-default/components/SidebarLinks.vue     | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/packages/@vuepress/theme-default/components/SidebarLinks.vue b/packages/@vuepress/theme-default/components/SidebarLinks.vue
index dfdb0bef07..d6b5ff7cdb 100644
--- a/packages/@vuepress/theme-default/components/SidebarLinks.vue
+++ b/packages/@vuepress/theme-default/components/SidebarLinks.vue
@@ -77,10 +77,23 @@ export default {
 function resolveOpenGroupIndex (route, items) {
   for (let i = 0; i < items.length; i++) {
     const item = items[i]
-    if (item.type === 'group' && item.children.some(c => c.type === 'page' && isActive(route, c.path))) {
+    if (descendantIsActive(route, item)) {
       return i
     }
   }
   return -1
 }
+
+function descendantIsActive (route, item) {
+  if (item.type === 'group') {
+    return item.children.some(child => {
+      if (child.type === 'group') {
+        return descendantIsActive(route, child)
+      } else {
+        return child.type === 'page' && isActive(route, child.path)
+      }
+    })
+  }
+  return false
+}
 </script>