Clear prevCallbacks on detach()

diff --git a/extras/synchronizer.js b/extras/synchronizer.js
index e0459fc..fdfec9f 100644 (file)
--- a/extras/synchronizer.js
+++ b/extras/synchronizer.js
@@ -123,6 +123,7 @@ Dygraph.synchronize = function(/* dygraphs..., opts */) {
       // release references & make subsequent calls throw.
       dygraphs = null;
       opts = null;
+      prevCallbacks = null;
     }
   };
 };