屌你老母邊撚個發明type script

0 == [] 成立唔等於 []係false
你試下if([]){console.log("hi")}就知
唔好用comparision 去判斷TRUE FALSE

呢個情況有啲特別，state係個number
number係immutable

array 同 object做arithmetic 同 comparision果陣會做type conversion 轉番做primitive type 先
array會call .join("")
object 會call .toString()

1) 0 == []
0 == [].join("")
0 == "" , true

2) "0" == []
"0" == [].join("")
"0" == "", false

Primitives 係 passed by value
https://stackoverflow.com/questions/13104494/does-javascript-pass-by-reference

State係immutable
Local variables係mutable

exaxtly

如果state係object就要至少shallow copy一次