Your browser timezone and your IP timezone are two different answers
Have you ever called Intl.DateTimeFormat().resolvedOptions().timeZone in your browser, compared it with an IP-geolocation-based "my timezone" result, and gotten two different answers? Neither answer is wrong. They answer two different questions. Here is how they differ, why a mismatch is usually normal, and why a bare UTC offset is never enough to define a timezone. Your browser timezone: what…
Have you ever noticed that your browser's timezone and your IP-based timezone can be different? This is completely normal and expected. Your browser's timezone is determined by your operating system, while the IP-based timezone is estimated from your egress IP address using a GeoIP database. These two timezones can differ due to various factors such as VPN/VPN, corporate egress, remote desktop/ cloud VM, manually changed system timezone, and stale or coarse GeoIP data.
It is important to understand the difference between these two timezones, especially if your application relies on them for scheduling, logging, or analytics. A common mistake is to use UTC offsets instead of IANA time zone identifiers, as offsets are only a snapshot and do not take daylight saving time into account. Use IANA identifiers like Asia/Shanghai or America/Chicago in code, APIs, and databases to ensure accurate time zone information.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
