CategoryIndex: move loading sub categories to separate function

src/CategoryIndex.js

@@ -21,6 +21,18 @@ CategoryIndex.prototype.open = function () {
     return
   }
 
+  this._loadChildrenCategories()
+}
+
+CategoryIndex.prototype.recalc = function () {
+  for (var k in this.childrenCategories) {
+    if (this.childrenCategories[k]) {
+      this.childrenCategories[k].recalc()
+    }
+  }
+}
+
+CategoryIndex.prototype._loadChildrenCategories = function () {
   this.childrenCategories = {}
 
   for (var i = 0; i < this.data.subCategories.length; i++) {
@@ -40,14 +52,6 @@ CategoryIndex.prototype.open = function () {
   }
 }
 
-CategoryIndex.prototype.recalc = function () {
-  for (var k in this.childrenCategories) {
-    if (this.childrenCategories[k]) {
-      this.childrenCategories[k].recalc()
-    }
-  }
-}
-
 CategoryIndex.prototype._loadChildCategory = function (err, category) {
   if (err) {
     return