Function to generate a dynamic sorted calendar object in JavaScript.

generateCalendar.js

function makeCalendar(startYear, endYear) {
  let calendar = {};

  var dateA = new Date(startYear, 0, 1, 0, 0, 0);
  var dateB = new Date(endYear, 11, 36, 0, 0, 0);
  for (
    var myDate = dateA;
    myDate <= dateB;
    myDate = new Date(myDate.getTime() + 1000 * 60 * 60 * 24)
  ) {
    let year = myDate.getFullYear();
    let month = myDate.getMonth() + 1;
    let dayOfMonth = myDate.getDate();
    let dayOfWeek = myDate.getDay() + 1;
    
    if ( calendar[year] == undefined ){
      calendar[year] = {};
    }
    if ( calendar[year][month] == undefined ){
      calendar[year][month] = {};
    }
    // console.log(year, month, dayOfMonth, dayOfWeek);
    calendar[year][month][dayOfMonth] = {};
    calendar[year][month][dayOfMonth].dayOfWeek = dayOfWeek;
  }
  return calendar;
}