倒數第二天！
今天的主題是「Javascript的奇怪地方」

BANANA

因為中間的 ++“a“ 部分會出現解析失敗，會回傳NaN，所以就變成baNaNa，然後再轉成小寫就變成banana了。

變數的運算

你永遠不知道Javascript的變數運算會發生什麼事。

型態及判斷

不多說了，上圖。

JSFuck

不知道各位有沒有聽過一個程式語言叫brainfuck，他是一個利用8個符號就可以撰寫程式的一個程式語言。

而利用Js本身的特性，你可以只使用六個字元，就湊出所有你要的東西。

舉例來說，你如果需要一個”a”，![]可以是一個‘false’，所以![][1]就是’a’，1又可以用+!![]來形成，所以就是![][+!![]]，如此精妙節儉的方式就可以得到一個’a’。

下面是一個簡單的Hello World輸出範例。

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void

JS有一個運法叫做void，他會執行一個計算時，然後回傳undefined，比如void fun()，他就會執行那個函式，但回傳undefined。

據說是因為undefined可以被當成變數名稱設值，但用void(0)產生的會是原本的undefined，所以為了就算undefined被當成變數名稱來用，用void(0)還是可以用。

==

在Javascript中，判斷是否相等有兩個二元運算子，分別是==跟===，==是會有一些神奇隱轉在裡面的，===則是維持原本的型態，所以一般建議全部採用===，比較不會踩到一些奇怪的坑。

總結

Javascript有各種各式各樣奇怪的坑，就像一盒巧克力，你永遠不知道下一口是什麼味道（X）

上面寫的也僅僅只是冰山一角。

希望各位未來如果有機會寫Javascript，可以隨心所欲不踩坑。

本期meme