See demo on Codepen: https://codepen.io/comehope/pen/erRzzR
Watch interactive screencast on Scrimba: https://scrimba.com/p/pEgDAM/cwrJys7
Read annotated source on Segmentfault(zh-cn): https://segmentfault.com/a/1190000014700727
Inspired by: Online Tutorials Channel https://www.youtube.com/watch?v=Urz50nJNa1E