📄️ Callbacks & Promise
A callback function is a function passed into another function as an argument, so a callback is a function will be executed after parent function is executed
📄️ Event Bubbling (propagation), Event Capturing
Bubbling
📄️ Hoisting
今天又要來介紹新的基礎觀念啦，在認識Hoisting之前，只單純知道宣告變數的方式，也沒有在乎它放在程式哪個段落會不會有影響。
📄️ Spread Operator… / Rest Parameter…
*the rest parameter is a feature that allows a function to accept an indefinite number of arguments*
📄️ Scope
Where and how to look for things. JS have two lexical scopes global and function