Generate lists of years, months and days

ymd.ts

import * as R from 'ramda';

// Used for HTML form where you can select individual year, month and day from dropdowns

// Last 20 years in reverse order
const years: number[] = R.unfold(
  (n: number) => n < new Date().getFullYear() - 20 || [n, n - 1],
  new Date().getFullYear(),
);
// All the calendar months                        
const months: number[] = R.unfold(
  (n: number) =>
    n > 11 ? false : [new Date(0, n).toLocaleString('en-US', { month: 'long' }), n + 1],
  0,
);
// 31 days - tweaking the number of days based on month selected would require additional scripting
const days: number[] = R.unfold((n: number) => n > 31 || [n, n + 1], 1);