See demo on Codepen: https://codepen.io/comehope/pen/XqYroe
Watch interactive screencast on Scrimba: https://scrimba.com/p/pEgDAM/c7EbPuW
Read annotated source on Segmentfault(zh-cn): https://segmentfault.com/a/1190000014836748
Inspired by: Sean Codes https://codepen.io/sean_codes/pen/xXYRbm