JS Implicit Binding


arrow 는 implicit this binding 안함
use strict difference
> [자바스크립트 this 바인딩 우선순위](https://jeonghwan-kim.github.io/2017/10/22/js-context-binding.html)

> [자바스크립트: function declaration와 Arrow Function의 this 스코프 차이](https://beomi.github.io/2017/07/12/understanding_js_scope_function_vs_arrow/)








