How to change Gregorian date to Persian date in JavaScript?

Question

Can anyone help me to change Gregorian date to Persian in JavaScript? I want to use it in HTML and JavaScript.

Answer 1

getPersianDate = (format) => { 
  let week = new Array("يكشنبه", "دوشنبه", "سه شنبه", "چهارشنبه", "پنج شنبه", "جمعه", "شنبه")
  let months = new Array("فروردين", "ارديبهشت", "خرداد", "تير", "مرداد", "شهريور", "مهر", "آبان", "آذر", "دي", "بهمن", "اسفند");
  let today = new Date();
  let d = today.getDay();
  let day = today.getDate();
  let month = today.getMonth() + 1;
  let year = today.getYear();
  year = (window.navigator.userAgent.indexOf('MSIE') > 0) ? year : 1900 + year;
  if (year == 0) {
      year = 2000;
  }
  if (year < 100) {
      year += 1900;
  }
  y = 1;
  for (i = 0; i < 3000; i += 4) {
      if (year == i) {
          y = 2;
      }
  }
  for (i = 1; i < 3000; i += 4) {
      if (year == i) {
          y = 3;
      }
  }
  if (y == 1) {
      year -= ((month < 3) || ((month == 3) && (day < 21))) ? 622 : 621;
      switch (month) {
          case 1:
              (day < 21) ? (month = 10, day += 10) : (month = 11, day -= 20);
              break;
          case 2:
              (day < 20) ? (month = 11, day += 11) : (month = 12, day -= 19);
              break;
          case 3:
              (day < 21) ? (month = 12, day += 9) : (month = 1, day -= 20);
              break;
          case 4:
              (day < 21) ? (month = 1, day += 11) : (month = 2, day -= 20);
              break;
          case 5:
          case 6:
              (day < 22) ? (month -= 3, day += 10) : (month -= 2, day -= 21);
              break;
          case 7:
          case 8:
          case 9:
              (day < 23) ? (month -= 3, day += 9) : (month -= 2, day -= 22);
              break;
          case 10:
              (day < 23) ? (month = 7, day += 8) : (month = 8, day -= 22);
              break;
          case 11:
          case 12:
              (day < 22) ? (month -= 3, day += 9) : (month -= 2, day -= 21);
              break;
          default:
              break;
      }
  }
  if (y == 2) {
      year -= ((month < 3) || ((month == 3) && (day < 20))) ? 622 : 621;
      switch (month) {
          case 1:
              (day < 21) ? (month = 10, day += 10) : (month = 11, day -= 20);
              break;
          case 2:
              (day < 20) ? (month = 11, day += 11) : (month = 12, day -= 19);
              break;
          case 3:
              (day < 20) ? (month = 12, day += 10) : (month = 1, day -= 19);
              break;
          case 4:
              (day < 20) ? (month = 1, day += 12) : (month = 2, day -= 19);
              break;
          case 5:
              (day < 21) ? (month = 2, day += 11) : (month = 3, day -= 20);
              break;
          case 6:
              (day < 21) ? (month = 3, day += 11) : (month = 4, day -= 20);
              break;
          case 7:
              (day < 22) ? (month = 4, day += 10) : (month = 5, day -= 21);
              break;
          case 8:
              (day < 22) ? (month = 5, day += 10) : (month = 6, day -= 21);
              break;
          case 9:
              (day < 22) ? (month = 6, day += 10) : (month = 7, day -= 21);
              break;
          case 10:
              (day < 22) ? (month = 7, day += 9) : (month = 8, day -= 21);
              break;
          case 11:
              (day < 21) ? (month = 8, day += 10) : (month = 9, day -= 20);
              break;
          case 12:
              (day < 21) ? (month = 9, day += 10) : (month = 10, day -= 20);
              break;
          default:
              break;
      }
  }
  if (y == 3) {
      year -= ((month < 3) || ((month == 3) && (day < 21))) ? 622 : 621;
      switch (month) {
          case 1:
              (day < 20) ? (month = 10, day += 11) : (month = 11, day -= 19);
              break;
          case 2:
              (day < 19) ? (month = 11, day += 12) : (month = 12, day -= 18);
              break;
          case 3:
              (day < 21) ? (month = 12, day += 10) : (month = 1, day -= 20);
              break;
          case 4:
              (day < 21) ? (month = 1, day += 11) : (month = 2, day -= 20);
              break;
          case 5:
          case 6:
              (day < 22) ? (month -= 3, day += 10) : (month -= 2, day -= 21);
              break;
          case 7:
          case 8:
          case 9:
              (day < 23) ? (month -= 3, day += 9) : (month -= 2, day -= 22);
              break;
          case 10:
              (day < 23) ? (month = 7, day += 8) : (month = 8, day -= 22);
              break;
          case 11:
          case 12:
              (day < 22) ? (month -= 3, day += 9) : (month -= 2, day -= 21);
              break;
          default:
              break;
      }
  }
  if(format===null || format===undefined)
    return `${week[d]} ${day} ${months[month - 1]} ${year}`
  if(format==="y/m/d")
    return `${year}/${month}/${day}`;
  if(format==="d/m/y")
    return `${day}/${month}/${year}`;
}
console.log(getPersianDate());
console.log(getPersianDate("y/m/d"));
console.log(getPersianDate("d/m/y"));