Time Zone Detection via Historical UTC Offset Sampling
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Solution Overview
Problem
JavaScript lacks an API to fetch the user's operating system time zone setting, leading to inaccurate time displays due to failure in accounting for daylight savings time (DST) changes and hemispheric differences in DST rules, especially affecting regions like New Zealand.
Innovation Solution
A process involving a server that computes UTC offsets for specific dates to create a hash value representation for each time zone, which is then used by the client to look up the corresponding time zone name using a lookup table, accounting for DST changes and hemispheric differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If UTC offset for current date is fetched to determine time zone, then time zone lookup is simple, but daylight savings time changes and hemispheric differences are not properly accounted for
Solution Approach 1:
The patent pre-computes UTC offsets for multiple specific dates throughout the year (including dates before, during, and after DST transitions) and stores them in a lookup table. This preliminary action enables the system to accurately determine time zones by comparing historical offset patterns rather than relying on current date only, thereby resolving the contradiction between simple lookup and accurate DST accounting.
2Device complexity
If northern hemisphere time zone is used for New Zealand clients, then time zone implementation is simplified, but inaccurate times are displayed during southern hemisphere summer
Solution Approach 1:
The patent changes the parameter used for time zone identification from simple UTC offset to a composite signature derived from multiple UTC offsets at different dates. This allows the system to distinguish between time zones with identical current offsets but different DST patterns (such as New Zealand vs. northern hemisphere time zones), thereby maintaining implementation simplicity while improving time display accuracy for all regions.
Data Source
AI summary
Detecting time zones using historical date sampling is disclosed. In various embodiments, an offset between a system time and a reference time is determined for each of a plurality of sample points, to produce a resulting set of offsets. A representation of the set of offsets is computed. The representation of the set of offsets is used as a key to look up a time zone associated with the system.