From 4da350ebfcaacc53d74fe08d39e1ff42b78e9449 Mon Sep 17 00:00:00 2001
From: Jens Langhammer <jens.langhammer@beryju.org>
Date: Sat, 14 May 2022 12:42:13 +0200
Subject: [PATCH] web: fix dateTimeLocal() dropping local timezone

closes #2860

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>
---
 web/src/utils.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/web/src/utils.ts b/web/src/utils.ts
index 5713acb44..369c5a757 100644
--- a/web/src/utils.ts
+++ b/web/src/utils.ts
@@ -97,6 +97,10 @@ export function dateTimeLocal(date: Date): string {
     // milliseconds, which the input field doesn't like (on chrome, on firefox its fine)
     // On chrome, setting .valueAsNumber works, but that causes an error on firefox, so go
     // figure.
-    const parts = date.toISOString().split(":");
+    // Additionally, toISOString always returns the date without timezone, which we would like
+    // to include for better usability
+    const tzOffset = new Date().getTimezoneOffset() * 60000; //offset in milliseconds
+    const localISOTime = new Date(date.getTime() - tzOffset).toISOString().slice(0, -1);
+    const parts = localISOTime.split(":");
     return `${parts[0]}:${parts[1]}`;
 }