Merge branch 'feature/tipEmpty' into release/5.2

@@ -31,7 +31,7 @@ var $tip, tipItime;
 function show(con, dur) {
 function show(con, dur) {
     var content, duration;
     var content, duration;
 
 
-    if (typeof con === 'undefined') {
+    if (typeof con === 'undefined' || con === '') {
         return;
         return;
     }
     }