Creates an ics birthday calendar from a space separated text file (bdays_src.txt [same dir]) formatted like: [first name] [last name] [DD.MM.YYYY][os.EOL]

birthdays.js

const fs = require('fs')
const os = require('os')

const dateToIcsString = date => "" + date.getFullYear() + (date.getMonth()+1).toString().padStart(2, '0') + date.getDate().toString().padStart(2,'0');

var f
try {
  f = fs.readFileSync('bdays_src.txt', 'utf8')
} catch (err) {
  console.error(err)
}

var data = f.split(os.EOL)
data = data.map(v => v.split(' '))

var bdays = "" 
var id = 0

data.forEach(v => {
  var date = new Date(v[2].split(".").reverse().join("-")) 
  var dateEnd = new Date(date)
  dateEnd.setDate(dateEnd.getDate() + 1)

  const lastName = v[1]

  const icsEventTemplate = `BEGIN:VEVENT
DTSTART;VALUE=DATE:${dateToIcsString(date)}
DTEND;VALUE=DATE:${dateToIcsString(dateEnd)}
RRULE:FREQ=YEARLY
DTSTAMP:20201012T095216Z
UID:587id060i821ren432uo8rklt4${id++}@google.com
CREATED:20201012T095002Z
DESCRIPTION:
LAST-MODIFIED:20201012T095002Z
LOCATION:
SEQUENCE:0
STATUS:CONFIRMED
SUMMARY:${v[0]} ${lastName}${lastName[lastName.length-1]=='s' ? '\'' : '\'s'} Birthday
TRANSP:TRANSPARENT
BEGIN:VALARM
ACTION:DISPLAY
DESCRIPTION:This is an event reminder
TRIGGER:-P0DT19H0M0S
END:VALARM
END:VEVENT`

  bdays += icsEventTemplate+os.EOL
})

const out = `BEGIN:VCALENDAR
PRODID:-//Google Inc//Google Calendar 70.9054//EN
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:SAP Birthdays
X-WR-TIMEZONE:Europe/Berlin
X-WR-CALDESC:Birthdays of Colleagues at SAP
${bdays}END:VCALENDAR
`
fs.writeFile('birthdays.ics', out, (err)=>{if (err) console.log(err)})