Promise 참고시.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise Image

Arrow Function 참고시
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

A Guide to Creating and Hosting a Personal Website on GitHub
http://jmcglone.com/guides/github-pages/

video 겹치게 배치하기 위해
https://www.w3schools.com/jsref/prop_style_position.asp

markdown syntax 참고시
https://daringfireball.net/projects/markdown/syntax