text: //days
  const days = document.querySelectorAll(".day");
  
  //days list
  const days_list = ["sundays","mondays","tuesdays","wednesdays","thursday","fridays","saturdays"];
  
  //configs
  const dayNames = ["Sun","Mon","Tue","Wed","Thu","Fri","Sat"];
  const monthNames = ["Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"];
  const month_day = [31,28,31,30,31,30,31,31,30,31,30,31];
  
  //now date object
  const now = new Date();
  const now_month = now.getMonth();
  const now_month_name = monthNames[now_month];
  const now_day = now.getDay();
  const now_day_name = dayNames[now.getDay()];
  const now_day_number = now.getDate();
  const now_year = now.getFullYear(); 
  const now_hour = now.getHours();
  const now_min = now.getMinutes();
  
  //week lists
  const weeks_default = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
  let weeks = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
  
  //up down buttons
  const up = document.querySelector("#month_up");
  const down = document.querySelector("#month_down");
  
  // date object
  let nm = now_month+1;
  let ny = now_year;
  function showDates(a){
  if(((nm+a)/12) > 1){
      nm -= 12;
      ny += 1;
  }
  if(((nm+a)/12) <= 0){
      nm += 12;
      ny -= 1;
  }
  var x = `${nm+a}/1/${ny}`;
  const date = new Date(x);
  let value = date.getDay();
  if(value != 0){
      value -= 1;    
  }else{
      if((value+7) != 7){
          value += 7;
      }
  }
  weeks = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
  let day;
  for (let i = 0; i < days.length; i++) {
      day = days[i]
      if (weeks[i] != 0) {
          day.textContent = weeks[i];
      } 
  }
  
  for (let i = 1; i < month_day[date.getMonth()]+1; i++) {
      weeks[value] = i;
      value++;
  } 
  
  for (let i = 0; i < days.length; i++) {
      day = days[i]
      if (weeks[i] != 0) {
          day.textContent = weeks[i];
          if(weeks[i] == now_day_number){
              if(a==0){
              day.className = day.className + " today"; }
          }else{
              day.className = "day";
          }
      }else{
          day.textContent = "";
      }
  }
  //month_name config
  document.querySelector("#month_name").textContent = monthNames[nm+a-1] + " " + ny;
  }
  
  //up-down event listener
  up.addEventListener("click",monthUp);
  down.addEventListener("click",monthDown);
  window.addEventListener("load",showDates(0));
  
  let number_month = 0;
  
  // monthUp
  function monthUp(e){
      number_month--;
      showDates(number_month);
      e.preventDefault();
  }
  
  //monthDown
  function monthDown(e){
      number_month++;
      showDates(number_month);
      e.preventDefault();
  }
  
  //getDate
  function getDate(a){
      switch (a) {
          case 1:
              return `${now_month_name} ${now_day_number}, ${now_year}`;
              break;
          case 2:
              return `${now_day_number}/${now_month+1}/${now_year}`;
              break;
          case 3:
              return `${now_month+1}/${now_day_number}/${now_year}`;
              break;
          default:
              return `${now_day_number} ${now_month_name} ${now_year}`;
              break;
      }
  }
  
  //getHour
  function getHour(){
      return `${now_hour}:${now_min}`;
  }
  