Move events in range x days

// Variables used by Scriptable.
// These must be at the very top of the file. Do not edit.
// icon-color: blue; icon-glyph: magic;
let now = new Date()
let datePick = new DatePicker()

//setup the date picker default date
datePick.initialDate = new Date(now.getFullYear(),now.getMonth(),now.getDate(),00,00)

let alerter

createAlert('Next, please pick the start date of the timeframe to look for events',0)
await alerter.present()
let sourceDateStart = await datePick.pickDate()

createAlert('Next, please pick the end date of the timeframe to look for events',0)
await alerter.present()

let sourceDateEnd = await datePick.pickDate()
sourceDateEnd = new Date(sourceDateEnd.getFullYear(),sourceDateEnd.getMonth(),sourceDateEnd.getDate(),23,59)

createAlert('Next, please the number of days to shift the events that are found (i.e. +/- x number of days',1)
await alerter.present()
let dateShift = alerter.textFieldValue(0)
log(`dateShift value is ${dateShift}`)

log(`sourceDateStart is ${sourceDateStart}\nsourceDateEnd is ${sourceDateEnd}`)

let cals = await Calendar.presentPicker(false)
//log(cals)
let events = await CalendarEvent.between(sourceDateStart, sourceDateEnd,cals)
log(events)

events.forEach((event) => {
  event.removeAllRecurrenceRules()
  let destDate = event.startDate
  log(`destDate is ${destDate}`)
  destDate.setHours(event.startDate.getHours())
  destDate.setMinutes(event.startDate.getMinutes())
  destDate.setDate(Number(event.startDate.getDate()) + Number(dateShift))
  event['startDate']=destDate

  destDate.setHours(event.endDate.getHours())
  destDate.setMinutes(event.endDate.getMinutes())
  destDate.setDate(Number(event.endDate.getDate()) + Number(dateShift))
  event['endDate'] = destDate
  log(`destDate is ${destDate}`)
  log(`event ${event.title} now at ${event['startDate']} and ending at ${event['endDate']}`)
  event.addRecurrenceRule(RecurrenceRule.weekly(1))
  event.save()
})

function createAlert(prompt,textEntryField){
alerter=new Alert()
alerter.message = prompt
alerter.addAction("OK")
if(textEntryField==1)alerter.addTextField('Days to shift events', '')
}