See demo on Codepen: https://codepen.io/comehope/pen/yqrNJm
Watch interactive video on Scrimba: https://scrimba.com/p/pEgDAM/cPEygSr
Read annotated source on Segmentfault(zh-cn): https://segmentfault.com/a/1190000015997373
Inspired by: Katy DeCorah https://codepen.io/katydecorah/pen/uIEFy