From b7f90368ee771a7e57def6f261f3d267b5f3f210 Mon Sep 17 00:00:00 2001
From: Caridy <cpatino@salesforce.com>
Date: Mon, 11 Dec 2017 15:49:20 -0500
Subject: [PATCH] fixes issue #348: perf optimization during diffing algo to
 avoid calling addVNodes and removeVNodes when there is nothing to do.

---
 src/snabbdom.ts | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/snabbdom.ts b/src/snabbdom.ts
index ed7b524..9b6b44d 100644
--- a/src/snabbdom.ts
+++ b/src/snabbdom.ts
@@ -240,11 +240,13 @@ export function init(modules: Array<Partial<Module>>, domApi?: DOMAPI) {
         }
       }
     }
-    if (oldStartIdx > oldEndIdx) {
-      before = newCh[newEndIdx+1] == null ? null : newCh[newEndIdx+1].elm;
-      addVnodes(parentElm, before, newCh, newStartIdx, newEndIdx, insertedVnodeQueue);
-    } else if (newStartIdx > newEndIdx) {
-      removeVnodes(parentElm, oldCh, oldStartIdx, oldEndIdx);
+    if (oldStartIdx <= oldEndIdx || newStartIdx <= newEndIdx) {
+      if (oldStartIdx > oldEndIdx) {
+        before = newCh[newEndIdx+1] == null ? null : newCh[newEndIdx+1].elm;
+        addVnodes(parentElm, before, newCh, newStartIdx, newEndIdx, insertedVnodeQueue);
+      } else {
+        removeVnodes(parentElm, oldCh, oldStartIdx, oldEndIdx);
+      }
     }
   }