【LINE Bot】GASを使って、LINE Botを作成！

const ACCESSTOKEN = "自身のチャネルアクセストークンを入力";  // ①
const URL = "https://api.line.me/v2/bot/message/reply";
 
function doPost(e) {
  let events = JSON.parse(e.postData.contents).events;
  events.forEach(function(event) {
    if((event.type == "message") && (event.message.type == "text")) {
      reply(event);
    }
  });
}
                 
function reply(event) {
  const calenderID = CalendarApp.getCalendarById("自身のカレンダーIDを入力する");  // ②
  const myEvents = calenderID.getEventsForDay(new Date());
  const messageText = event.message.text === "スケジュール"
  // スケジュール以外の文字が送信された場合の処理
  if(!messageText){
    UrlFetchApp.fetch(URL, {
      "headers": {
        "Content-Type": "application/json; charset=UTF-8",
        "Authorization": "Bearer " + ACCESSTOKEN,
      },
      "method": "post",
      "payload": JSON.stringify({
        "replyToken": event.replyToken,
        "messages": [{
          "type": "text",
          "text": "「スケジュール」と入力してください",
        }],
      }),
    });
  }
  // "スケジュール"と送信された場合、カレンダーに予定が1つもなかった場合の処理
  if(myEvents.length > 0){
    var message = "";
    for(let i=0; i<myEvents.length; i++){
      let title = myEvents[i].getTitle();
      let start = Utilities.formatDate(myEvents[i].getStartTime(), "JST", "HH:mm");
      let end = Utilities.formatDate(myEvents[i].getEndTime(), "JST", "HH:mm");
      message += `\n■　予定${i+1}\n⏰　${start}~${end}\n⭐【${title}】\n`
    }
    UrlFetchApp.fetch(URL, {
      "headers": {
        "Content-Type": "application/json; charset=UTF-8",
        "Authorization": "Bearer " + ACCESSTOKEN,
      },
      "method": "post",
      "payload": JSON.stringify({
        "replyToken": event.replyToken,
        "messages": [{
          "type": "text",
          "text": message,
        }],
      }),
    });

  }else{
    UrlFetchApp.fetch(URL, {
      "headers": {
        "Content-Type": "application/json; charset=UTF-8",
        "Authorization": "Bearer " + ACCESSTOKEN,
      },
      "method": "post",
      "payload": JSON.stringify({
        "replyToken": event.replyToken,
        "messages": [{
          "type": "text",
          "text": "本日予定はありません",
        }],
      }),
    });
  }
}