Minersphere::Index::Date calculator

This is a simple date calculator that I made in a single afternoon (and some of the nighttime too I guess) on June 4th 2025 based on the XKCD calculator engine I made a few months earlier. Features and quirks:

Arbitrary precision integers;
Dates are input in the year-month-day format;
Dates before year 1 are written with negative numbers (5 BC would be year -4) in the inputs;
This uses the proleptic Gregorian calendar.

The source code is at script.js, while the source code of the date engine is at MinersDate.js.

Also! Default values are dates/numbers that I really like referencing for whatever reason. Two are from webshows, one is a "mind inside joke" and the other is from a conworld :)

Calculators

Day addition

Date:
Days to add:

Sum:

Date difference

Date 1:
Date 2:

Difference: days

Date to ordinal

Date:

Ordinal:

Ordinal to date

Ordinal:

Date: