How is date conversion implemented when switch different calendars?

[olfatgh]

using setting plugin to enable user to use both Gregorian and Arabic calendars, but seems like conversion dates is not prober example: select date 09/01/1386 in Arabic calendar change calendar to Gregorian the selected date is 30/04/1966 while it must be 29/04/1966

so theres one day difference

[shahabyazdi]

When calculating the lunar month, there may be a discrepancy of one or, at most, two days. This variation is tied to the calculation method employed by this library, which is based on the information provided in the following reference: https://en.wikipedia.org/wiki/Tabular_Islamic_calendar.

See also: https://shahabyazdi.github.io/react-multi-date-picker/calendars/#calendars