任意の条件でホテルの空室が発生したら通知するプログラムを作りました

function sendMail(str) {  //手順1
  const recipient = '自分のGmailアドレス';
  const subject = '空室ぽよ';
 
  const body = '空室ぽよ。\n\n' + str
 
  const options = {
     from: '自分のGmailアドレス',
     name: 'ぽよさん'
     };  
 
  GmailApp.sendEmail(recipient, subject, body, options);
 
}

function fetchVacantHotels() {
  const uri = 'https://app.rakuten.co.jp/services/api/Travel/VacantHotelSearch/20170426?applicationId=取得したアプリケーションID&format=json&checkinDate=2023-08-04&checkoutDate=2023-08-06&largeClassCode=japan&middleClassCode=iwate&smallClassCode=morioka&adultNum=2'
  //手順2、手順3
  
  const options = {
    "method": 'get',
    //'headers': headers,
    "muteHttpExceptions" : true,
    "validateHttpsCertificates" : false,
    "followRedirects" : false,
  }

  try {
    const response = UrlFetchApp.fetch(uri, options)
    const res = JSON.parse(response);
    var str = ''
    var twinNum = 0
    
    res.hotels.forEach((hotel) => {
      var hotelName = ''
      var hotelInformationUrl = ''

      hotel.hotel.forEach((info) => {
        if('hotelBasicInfo' in info) {
          hotelName = info.hotelBasicInfo.hotelName
          hotelInformationUrl = info.hotelBasicInfo.hotelInformationUrl

        } else {
          info.roomInfo.forEach((roomBasicInfo) => {
            if('roomBasicInfo' in roomBasicInfo) {
              var roomName = roomBasicInfo.roomBasicInfo.roomName
              var reserveUrl = roomBasicInfo.roomBasicInfo.reserveUrl

              if(roomName.indexOf('ツイン') != -1) {  //手順4
                twinNum++
                str += 'hotelName: ' + hotelName + '\n'
                    + 'hotelInformationUrl: ' + hotelInformationUrl + '\n'
                    + 'roomName: ' + roomName + '\n'
                    + 'reserveUrl: ' + reserveUrl + '\n\n'

              }

            }
          })
        }
      })
    })

    if(twinNum > 0) {
      sendMail(str)
    }

  } catch(e) {
    // 例外エラー処理
    Logger.log('Error:')
    Logger.log(e)
  }
}

function myFunction() {
  var str = fetchVacantHotels()
  
}