Scriptable script that powers a home screen widget

Day of March widget.js

// Variables used by Scriptable.
// These must be at the very top of the file. Do not edit.
// icon-color: deep-green; icon-glyph: calendar-alt;
let widget = createWidget()

if (!config.runsInWidget) {
  await widget.presentMedium()
}
Script.setWidget(widget)
Script.complete()

function createWidget() {
  let fontSize = 36
  switch (config.widgetFamily) {
    case "small": fontSize = 28; break;
    case "medium": fontSize = 36; break;
    case "large": fontSize = 48; break;
  }
  
  
  const widget = new ListWidget()
  let text = widget.addText("Today is")
  text.font = Font.mediumSystemFont(fontSize)
  text = widget.addText("March " + getToday())
  text.font = Font.boldSystemFont(fontSize)
  return widget
}

// Cribbed from https://github.com/mdayaram/calendar2020
function isLeapYear(date) {
  const year = date.getFullYear();
  if ((year & 3) != 0) return false;
  return ((year % 100) != 0 || (year % 400) == 0);
};

// Get Day of Year
function getDOY(date) {
  const dayCount = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
  const mn = date.getMonth();
  const dn = date.getDate();

  let dayOfYear = dayCount[mn] + dn;
  if (mn > 1 && isLeapYear(date)) dayOfYear++;
  return dayOfYear;
};

function dayOfMarch(dayOfYear = null) {
  if (dayOfYear === null) {
    const now = new Date();
    dayOfYear = getDOY(now);
  }

  return dayOfYear - 31 - 29;  // minus January and February.
}

function getToday() {
  const day = dayOfMarch();

  const ones = day % 10;
  const tens = (day % 100) - ones;

  let suffix;
  if (tens !== 10 && ones === 1) {
    suffix = "st";
  } else if (tens !== 10 && ones === 2) {
    suffix = "nd";
  } else if (tens !== 10 && ones === 3) {
    suffix = "rd";
  } else {
    suffix = "th";
  }
  
  return day.toString() + suffix
}