이벤트가 일어날때 사용하는 e는 어디에서 생기는거냐

https://stackoverflow.com/questions/35936365/what-exactly-is-the-parameter-e-event-and-why-pass-it-to-javascript-functions

 

https://developer.mozilla.org/en-US/docs/Web/Guide/Events/Creating_and_triggering_events

 

https://www.w3.org/TR/uievents/#event-flow