onload가 아닌 load 파라메터를 넘겨주어야 한다.
https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event
https://developer.mozilla.org/ko/docs/Web/API/EventTarget/addEventListener
https://opentutorials.org/course/1375/6761
onload가 아닌 load 파라메터를 넘겨주어야 한다.
https://developer.mozilla.org/en-US/docs/Web/API/Window/load_event
https://developer.mozilla.org/ko/docs/Web/API/EventTarget/addEventListener
https://opentutorials.org/course/1375/6761