CalculatorsLesson 172Free preview

Day of the Week

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Summary

Day of the Week counts the names of days for a specific date, for example for a schedule, archive, or data analysis. JavaScript provides getDay() with 0 for Sunday, while ISO standards use 1 for Monday to 7 for Sunday. Use a pure date and a consistent time zone so the results don't shift one day.

Key points

JavaScript: 0=Wednesday, 1=Tuesday, up to 6=Saturday
ISO 8601:1=Monday to 7=Wednesday
The time zone can shift the date if the clock is not turned.
Zeller's algorithm can count days without a library.
The name of the local day can be formatted with Intl.DateTimeFormat

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