CalculatorsLesson 170Free preview

Add or Subtract Days

This lesson is part of Web Developer Tools · All levels

Summary

The Add or Subtract Days tool adds or subtracts a number of days, weeks, months, or years from a date. For days, the addition can automatically exceed the month and year limits. For the month, results can be adjusted if the target date is not available, for example 31 January plus one month to the end of February.

Key points

Adding days can automatically pass the end of months and years
The new moon needs a rule of clamping for the 29-31
The year of the equinox affects the result of the addition of days
Save the date as a pure date without clock
Check the results with a calendar, not a 30-day assumption.

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