hotel stay cost

hotelStayCost.js

/**
 * Дано: день пребывания в отеле в рабочий день стоит 1000р, а в выходной 1500р. Задача: написать код который посчитает стоимость за пребывание в течении X дней с указанной даты
 */

const weekdayPrice = 1000;
const weekendsPrice = 1500;

// version 1
const stayCost1 = (daysAmount, startDate = new Date()) => {
  const currentDay = startDate.getDay();
  const weekDays = new Array(daysAmount)
  .fill(currentDay)
  .map((day, index) => (index + day) % 7 || 7);
  
  return weekDays.reduce((sum, day) => sum + (day > 5 ? weekendsPrice : weekdayPrice), 0)
}

// version 2
const stayCost2 = (daysAmount, startDate = new Date()) => {
  const currentDay = startDate.getDay();

  return new Array(daysAmount)
  .fill(0)
  .map((i, j) => i + j)
  .reduce((sum, dayIndex) => {
    const day = (dayIndex + currentDay) % 7 || 7;
    return sum + (day > 5 ? weekendsPrice : weekdayPrice);
  }, 0)
}


// version 3
const PRICE_STANDARD = 1000
const PRICE_WEEKEND = 1500
function datePrice(date) {
  return isWeekend(date) ? PRICE_WEEKEND : PRICE_STANDARD
}

function isWeekend(date) {
  const dayOfWeek = date.getDay();
  const dayOfWeekSaturday = 6;
  const dayOfWeekSunday = 0;
  return [dayOfWeekSaturday, dayOfWeekSunday].includes(dayOfWeek);
}

function bill(startDate, nights) {
  let sum = 0;
  for(let n = 0; n < nights; n++){
    let date = new Date();
    date.setDate(startDate.getDate() + n);
    sum = sum + datePrice(date);
  }
  return sum;
}

console.log(bill(new Date(2021, 7, 30), 1)) // 1000
console.log(bill(new Date(2021, 7, 31), 1)) // 1500
console.log(bill(new Date(2021, 7, 25), 7)) // 8000
console.log(bill(new Date(2021, 7, 26), 6)) // 6500
console.log(bill(new Date(2021, 7, 27), 5)) // 5500