Calendar.jsx

....
import {
  format,
  startOfWeek,
  addDays,
  startOfMonth,
  endOfMonth,
  endOfWeek,
  isSameMonth,
  isSameDay
} from "date-fns";

const Calendar = () => {
....
  const generateDatesForCurrentWeek = (date, selectedDate, activeDate) => {
    let currentDate = date;
    const week = [];
    for (let day = 0; day < 7; day++) {
      const cloneDate = currentDate;
      week.push(
        <div
          className={`day ${
            isSameMonth(currentDate, activeDate) ? "" : "inactiveDay"
          } ${isSameDay(currentDate, selectedDate) ? "selectedDay" : ""}
          ${isSameDay(currentDate, new Date()) ? "today" : ""}`}
          onClick={() => {
            setSelectedDate(cloneDate);
          }}
        >
          {format(currentDate, "d")}
        </div>
      );
      currentDate = addDays(currentDate, 1);
    }
    return <>{week}</>;
  };

  const getDates = () => {
    const startOfTheSelectedMonth = startOfMonth(activeDate);
    const endOfTheSelectedMonth = endOfMonth(activeDate);
    const startDate = startOfWeek(startOfTheSelectedMonth);
    const endDate = endOfWeek(endOfTheSelectedMonth);

    let currentDate = startDate;

    const allWeeks = [];

    while (currentDate <= endDate) {
      allWeeks.push(
        generateDatesForCurrentWeek(currentDate, selectedDate, activeDate)
      );
      currentDate = addDays(currentDate, 7);
    }

    return <div className="weekContainer">{allWeeks}</div>;
  };

....
}