# number

a = 100; a = 10e5; a = 0100; a = 0x100; a = Number('100')

a = Number('100a') => NaN

**isNaN(a) //唯一判斷NaN 的方法**

就連 NaN == NaN or NaN === NaN 都會 false

parseInt(string, 10); //字串, 進制

使用 + 可以自動轉型

JS 比對整數

最大安全整數

Number.MAX\_SAFE\_INTEGER

以上就不能相信了

浮點數可以表現極大值，但有精準度問題

chrome 可以算 bigint

後面 + n

2n \*\* 1000000n // \*\* = ^

bigint 可以做計算，但是當除法有餘數時，會自動被省略

浮點數

0.1 + 0.2

(0.1 + 0.2).toFixed(1)

**+(0.1 + 0.2).toFixed(1)**

(0.000001).toString (0.0000001).toString


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