fix: update offset error with daylight saving time

moment · Dec 5, 2024 · 76011ad · 76011ad
1 parent 4b7ce20
commit 76011ad
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diff --git a/moment-timezone.js b/moment-timezone.js
@@ -652,7 +652,15 @@
 				offset = offset / 60;
 			}
 			if (mom.utcOffset !== undefined) {
+				var _offset = mom._offset;
 				var z = mom._z;
+				if (keepTime && typeof keepTime === 'number' && _offset && -offset > _offset) {
+					var preMom = moment(mom.valueOf() - (-offset - _offset) * 60 * 1000);
+					var preOffset = mom._z.utcOffset(preMom);
+					if (offset !== preOffset) {
+						keepTime = false;
+					}
+				}
 				mom.utcOffset(-offset, keepTime);
 				mom._z = z;
 			} else {

diff --git a/tests/moment-timezone/manipulate.js b/tests/moment-timezone/manipulate.js
@@ -15,6 +15,26 @@ exports.manipulate = {
 	},
 
 	add : function (t) {
+		t.equal(
+			moment('2024-09-07T00:00:00-04:00').tz('America/Santiago').add(1, 'days').format(),
+			'2024-09-08T01:00:00-03:00',
+			"adding 1 day while crossing a DST boundary should not affect time."
+		);
+		t.equal(
+			moment('2024-09-07T04:00:00-04:00').tz('America/Santiago').add(1, 'days').format(),
+			'2024-09-08T04:00:00-03:00',
+			"adding 1 day while crossing a DST boundary should not affect time."
+		);
+		t.equal(
+			moment('2024-08-08T00:00:00-04:00').tz('America/Santiago').add(1, 'months').format(),
+			'2024-09-08T01:00:00-03:00',
+			"adding 1 day while crossing a DST boundary should not affect time."
+		);
+		t.equal(
+			moment('2024-08-08T04:00:00-04:00').tz('America/Santiago').add(1, 'months').format(),
+			'2024-09-08T04:00:00-03:00',
+			"adding 1 day while crossing a DST boundary should not affect time."
+		);
 		t.equal(
 			moment('2012-10-28 00:00:00+01:00').tz('Europe/London').add(1, 'days').format(),
 			'2012-10-29T00:00:00Z',