calculate days from full date in javascript code example

Example 1: javascript difference between two dates in days

/* difference between date1 and date2 in days (date2 - date1) */
/* date1 and date 2 are already javascript date objects */
function dateDifference(date2, date1) {
    const _MS_PER_DAY = 1000 * 60 * 60 * 24;

    // Discard the time and time-zone information.
    const utc1 = Date.UTC(date1.getFullYear(), date1.getMonth(), date1.getDate());
    const utc2 = Date.UTC(date2.getFullYear(), date2.getMonth(), date2.getDate());

    return Math.floor((utc2 - utc1) / _MS_PER_DAY);
}

Example 2: how to calculate the number of days between two dates in javascript

function javascript (date1, date2) {
   let oned = 24 * 60 * 60 * 1000;
   return Math.ceil((date2 - date1) / oned);
}

function javascript(date1, date2) {
	return new Date(date2 - date1).getDate() - 1
}

function javascript(date1, date2) {
  return Math.ceil((date2 - date1) / 8.64e7);
}