npm i
npm run dev
open http://localhost:3000/webhook
using ngrok
open tunnel for test
ngrok http 3000
copy tunnel link and paste it on https://developers.line.biz/console/ -> Messaging API -> Webhook URL
for credentials.json
credentials data
go to https://console.cloud.google.com/apis/credentials
and download Download OAuth client
from OAuth 2.0 Client IDs section