对于循环在预订网站中不起作用，日期不是连续的

// JavaScript code for generating the calendar and handling month navigation
const calendarContainer = document.getElementById("calendar");
const prevMonthBtn = document.getElementById("prevMonth");
const nextMonthBtn = document.getElementById("nextMonth");
const currentMonthYear = document.getElementById("currentMonthYear");

const daysOfWeek = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
const months = [
  "January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December"
];

const currentDate = new Date();
let currentMonth = currentDate.getMonth();
let currentYear = currentDate.getFullYear();

function generateCalendar() {
  const daysInMonth = new Date(currentYear, currentMonth + 1, 0).getDate();
  const firstDayIndex = new Date(currentYear, currentMonth, 1).getDay();

  calendarContainer.innerHTML = "";

  // Display days of the week at the top of the calendar
  for (const dayOfWeek of daysOfWeek) {
    const dayOfWeekDiv = document.createElement("div");
    dayOfWeekDiv.classList.add("day");
    dayOfWeekDiv.textContent = dayOfWeek;
    calendarContainer.appendChild(dayOfWeekDiv);
  }

  for (let i = 0; i < firstDayIndex; i++) {
    const dayDiv = document.createElement("div");
    dayDiv.classList.add("day");
    calendarContainer.appendChild(dayDiv);
  }

  for (let i = 1; i <= daysInMonth; i++) {
    const dayDiv = document.createElement("a");
    dayDiv.href = "entry.php";
    let __ryear = currentYear.toString();
    let __rmonth = currentMonth.toString();
    let daI = i.toString();
    let result1 = __ryear.concat(__rmonth);
    let result2 = result1.concat(daI);
    // let ruiue = result2;
    // let date6969 = i;

    // AJAX request to check if the date exists in the database
    let xhr = new XMLHttpRequest();
    xhr.open("GET", "http://localhost/irctclogin/check_date.php?date=" + result2, true);
    xhr.onreadystatechange = function() {
      if (xhr.readyState == 4 && xhr.status == 200) {
        let response = xhr.responseText;
        if (response == "exists") {

          // Date exists in the database, continue the program
          let bookStatus = "booked";
          dayDiv.classList.add("day", result2, bookStatus);
          dayDiv.textContent = i;
          calendarContainer.appendChild(dayDiv);
          // dayDiv.value = i;

        }
          else {
            let bookStatus = "available";
            dayDiv.classList.add("day", result2, bookStatus);
            dayDiv.textContent = i;
            calendarContainer.appendChild(dayDiv);
            // dayDiv.value = i;
            // console.log(i);
          }
        }
      }
      xhr.send();
    }

    currentMonthYear.textContent = `${months[currentMonth]} ${currentYear}`;
    // console.log(`${months[currentMonth]} ${currentYear}`);
  }

  prevMonthBtn.addEventListener("click", () => {
    if (currentMonth === 0) {
      currentMonth = 11;
      currentYear--;
    } else {
      currentMonth--;
    }
    generateCalendar();
  });

  nextMonthBtn.addEventListener("click", () => {
    if (currentMonth === 11) {
      currentMonth = 0;
      currentYear++;
    } else {
      currentMonth++;
    }
    generateCalendar();
  });

  generateCalendar();