fix issue with numbered TZID by always converting to string

(fixes jens-maus#311).

ical.js

@@ -81,20 +81,17 @@ const storeParameter = function (name) {
 };
 
 const addTZ = function (dt, parameters) {
-  const p = parseParameters(parameters);
-
-  if (dt.tz) {
+  if (dt && dt.tz) {
     // Date already has a timezone property
     return dt;
   }
 
-  if (parameters && p && dt) {
-    dt.tz = p.TZID;
-    if (dt.tz !== undefined) {
-      // Remove surrounding quotes if found at the beginning and at the end of the string
-      // (Occurs when parsing Microsoft Exchange events containing TZID with Windows standard format instead IANA)
-      dt.tz = dt.tz.replace(/^"(.*)"$/, '$1');
-    }
+  const p = parseParameters(parameters);
+  if (parameters && p && dt && typeof p.TZID !== 'undefined') {
+    dt.tz = p.TZID.toString();
+    // Remove surrounding quotes if found at the beginning and at the end of the string
+    // (Occurs when parsing Microsoft Exchange events containing TZID with Windows standard format instead IANA)
+    dt.tz = dt.tz.replace(/^"(.*)"$/, '$1');
   }
 
   return dt;

test/test.js

@@ -1038,6 +1038,19 @@ vows
           assert.equal(event.end.toDateString(), new Date(2024, 1, 22).toDateString());
         }
       }
+    },
+    'with test_with_int_tzid.ics': {
+      topic() {
+        return ical.parseFile('./test/test_with_int_tzid.ics');
+      },
+      'checking for TZID': {
+        topic(topic) {
+          return _.values(topic)[0];
+        },
+        'task completed'(task) {
+          assert.equal(task.summary, 'test export import');
+        }
+      }
     }
   })
   .export(module);

test/test_with_int_tzid.ics

@@ -0,0 +1,66 @@
+BEGIN:VCALENDAR
+BEGIN:VEVENT
+CREATED:20231214T150120Z
+LAST-MODIFIED:20231214T150224Z
+DTSTAMP:20231214T150224Z
+UID:df21da35-3a0b-434a-9211-da9f9095fb16
+SUMMARY:test export import
+CATEGORIES:Professionnel
+DTSTART;TZID=Europe/Paris:20231215T150000
+DTEND;TZID=Europe/Paris:20231215T160000
+TRANSP:OPAQUE
+LOCATION:dijon
+DESCRIPTION;ALTREP="data:text/html,test":test
+END:VEVENT
+BEGIN:VTIMEZONE
+TZID: 1
+BEGIN:STANDARD
+DTSTART:16010101T030000
+TZOFFSETFROM:+0200
+TZOFFSETTO:+0100
+RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10
+END:STANDARD
+BEGIN:DAYLIGHT
+DTSTART:16010101T020000
+TZOFFSETFROM:+0100
+TZOFFSETTO:+0200
+RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3
+END:DAYLIGHT
+END:VTIMEZONE
+BEGIN:VEVENT
+CREATED:20240229T160626Z
+LAST-MODIFIED:20231221T141000Z
+DTSTAMP:20231221T141000Z
+UID:040000008200E00074C5B7101A82E008000000008D1F7DAB8632DA01000000000000000
+ 0100000008EF89A92C90D1342BF1F2CB714276CCC
+SUMMARY:Atelier groupes portail/Nuage
+PRIORITY:5
+STATUS:CONFIRMED
+DTSTART;TZID= 1:20240108T110000
+DTEND;TZID= 1:20240108T120000
+CLASS:PUBLIC
+DESCRIPTION;LANGUAGE=fr-FR:Désolé pour ces changements de date\, j'espèr
+ e que ce dernier créneau conviendra à tout le monde. \n\nJe vous propose 
+ cette date pour un atelier sur les soucis avec les commandes à passer sur 
+ les serveurs nextcloud pour la mise en place des groupes. Dites moi si ça 
+ ne convient pas. Merci !\n
+TRANSP:OPAQUE
+SEQUENCE:3
+LOCATION;LANGUAGE=fr-FR:https://visio-agents.education.fr/
+X-MICROSOFT-CDO-APPT-SEQUENCE:3
+X-MICROSOFT-CDO-OWNERAPPTID:2122095757
+X-MICROSOFT-CDO-BUSYSTATUS:TENTATIVE
+X-MICROSOFT-CDO-INTENDEDSTATUS:BUSY
+X-MICROSOFT-CDO-ALLDAYEVENT:FALSE
+X-MICROSOFT-CDO-IMPORTANCE:1
+X-MICROSOFT-CDO-INSTTYPE:0
+X-MICROSOFT-DONOTFORWARDMEETING:FALSE
+X-MICROSOFT-DISALLOW-COUNTER:FALSE
+X-MICROSOFT-LOCATIONDISPLAYNAME:https://visio-agents.education.fr/
+X-MICROSOFT-LOCATIONSOURCE:None
+X-MICROSOFT-LATITUDE:0
+X-MICROSOFT-LONGITUDE:0
+X-MOZ-RECEIVED-SEQUENCE:3
+X-MOZ-RECEIVED-DTSTAMP:20231221T141000Z
+END:VEVENT
+END:VCALENDAR