See demo on Codepen: https://codepen.io/comehope/pen/RJjQYY
Watch interactive video on Scrimba: https://scrimba.com/p/pEgDAM/cLQLyTR
Read annotated source on Segmentfault(zh-cn): https://segmentfault.com/a/1190000015313341
Inspired by: Sean Free https://codepen.io/seanfree/pen/ZpKaVp