I want to find a public day in Jalali calendar, I use npm Jalali-moment with this code
var moment = require('jalali-moment');
moment().locale('fa').format('YYYY/M/D');
This site has done this which called تاریخ امروز But I don't know how he did it.
Is there a way to do this without manually entering information like this site( Garageband for windows )?

That's a good question, I used to want to do it before, but eventually I had to manually enter the information