[問題] Why NaN and Infinity are classified as the type of numbe

[freeman371 (自由人371)]

I have practiced Javascript for a long long time,
and there's always a contradiction, which has confused me so much.
That is, why NaN and Infinity are both types of “number”?
In mathematics,“Infinity”is just a concept, not a number.
“NaN”means“Not a number”on its literal meaning.
Obviously those are not“numbers.”
However, in Javascript, both“NaN”and“Infinity”are“number.”
You can try it like below:


    typeof NaN        // Returns“number”

    typeof Infinity   // Returns“number”


So what's the reason?
Could someone tell me the reason about this weird contradiction?

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→ ssccg: 不然你覺得是什麼type?
→ ssccg: 實作上來說這些只是特別的數字，可參考IEEE754
推 DolphinLinn: NaN is number type, and NaN != NaN
推 aspdoctor: 白馬是馬，白馬也非馬，就這個意思
推 Qiqi: 樓上不如講 色即是空，空即是色
推 visa9527: 就像 '' 也是 string 啊，明明就是空的東西
推 hijkxyzuw: 浮點數裡有定義 NaN ，所以在 C 裡也能用。
推 VdustR: null 也是 object 阿