GA4 自訂事件｜ga.js / gtag.js

REF

https://support.google.com/analytics/answer/10106774?hl=zh-Hant&ref_topic=10737980

https://support.google.com/analytics/answer/9234069

Gtag.js教學

https://developers.google.com/analytics/devguides/collection/gtagjs/events