index.html.in: return the empty string for unknown MARC zones

diff --git a/index.html.in b/index.html.in
index f6094fafa999961ba1abeb17c9f80968f1387903..b09f59a71df9b56c512c75fb5853291958649cfe 100644 (file)
--- a/index.html.in
+++ b/index.html.in
@@ -545,10 +545,10 @@
         BWI_WBL: 1
       };
 
-      /* The default. Obviously wrong for when we don't
-       * have the necessary data. */
-      let zone = 0;
-
+      /* Compute the zone (string) for the given origin/destination pair.
+       * If we don't know it or if you chose in invalid pair (destination
+       * not on the same line as your origin?) then the empty string is
+       * returned. */
       function compute_marc_zone(src, dest) {
         /* Forward direction key for zone_map */
         const fwd = src + "_" +  dest;
@@ -558,6 +558,10 @@
          * directions here. */
         const rev = dest + "_" +  src;
 
+        /* The default. Obviously wrong for when we don't
+         * have the necessary data. */
+        let zone = -1;
+
         if (zone_map[fwd]) {
           zone = zone_map[fwd];
         }
@@ -576,7 +580,7 @@
           case 4:
             return "Four Zone";
           default:
-            return "??? Zone";
+            return "";
         }
       }