See demo on Codepen: https://codepen.io/comehope/pen/vaPGRz
Watch interactive video on Scrimba: https://scrimba.com/p/pEgDAM/cz32DUd
Read annotated source on Segmentfault(zh-cn): https://segmentfault.com/a/1190000015982054
Inspired by: JR Halchak https://codepen.io/jrhalchak/pen/wKXqqX