js algorithm utility functions

utility.ts

// greatest common denominator
const gcd = (a, b) => b ? gcd(b, a % b) : a

// lowest common multiplier
const lcm = (a, b) => (a * b)/ gcd(a, b)

// some Date stuff for safe-keeping
const weekdayMonthFormat = {
  weekday: 'long',
  day: 'numeric',
  month: 'long',
  timeZone: 'Europe/Paris',
} as Intl.DateTimeFormatOptions;

const getFrenchMonths = () => {
  const now = new Date(Date.now());
  const availableDates = [];

  for (let i = (-1 * 7); i <= 0; i++) {
    const tempDate = new Date(Number(now));
    tempDate.setDate(now.getDate() + i);
    tempDate.setHours(12);

    const tempTime = ~~(tempDate.getTime() / 1e3);
    availableDates.push(getDateFromTimestamp(tempTime, weekdayMonthFormat));
  }

  return availableDates;
};

const getMidnightOfTimestamp = (time: number): number => {
  const midnight = new Date(time * 1e3).setHours(0, 0, 0, 0);
  return midnight / 1e3;
};