fix:guess timezone using moment
diff --git a/erpnext/www/book-appointment/index.js b/erpnext/www/book-appointment/index.js
index 6034f4e..1b7a801 100644
--- a/erpnext/www/book-appointment/index.js
+++ b/erpnext/www/book-appointment/index.js
@@ -33,9 +33,11 @@
     let offset = new Date().getTimezoneOffset();
     window.timezones.forEach(timezone => {
         let opt = document.createElement('option');
-        opt.value = timezone.offset;
-        opt.innerHTML = timezone.timezone_name;
-        opt.defaultSelected = (offset == timezone.offset)
+        opt.value = timezone;
+        if(timezone == moment.tz.guess()){
+            opt.selected = true;
+        }
+        opt.innerHTML = timezone;
         timezones_element.appendChild(opt)
     });
 }