https://webkit.org/blog/7846/concurrent-javascript-it-can-work/
https://medium.com/dev-channel/es6-modules-in-chrome-canary-m60-ba588dfb8ab7
http://2ality.com/2015/01/es6-destructuring.html
async/await
https://developers.google.com/web/fundamentals/getting-started/primers/async-functions?hl=ko
https://developers.google.com/web/fundamentals/primers/async-functions?hl=ko
custom element
https://www.youtube.com/watch?v=sK1ODp0nDbM
Websocket
https://developer.mozilla.org/ko/docs/WebSockets/Writing_WebSocket_client_applications
javascript template
https://github.com/PolymerLabs/lit-html