hijrah-date | Javascript date in the Hijrah calendar system | Date Time Utils library

The javascript implementation generates the class through an IIFE, which effectively provides a pattern for generating a 'private' API without prior native support. The init function itself could be considered part of the private API. While invoked, it's never actually exposed on the returned class. Further, init relies on certain private vars such as maxEpochDay which you have not declared.

Any function or variable not ultimately exposed on the returned class via the IIFE could be declared private with ts. Those which are defined on the prototype property in the IIFE could be included be added as class methods, which are public by default or can be marked for clarity.