Math.abs()

Math.abs() 函式會回傳一個數字的絕對值,即為:

Math.abs(x)=|x|={xifx>00ifx=0-xifx<0{\mathtt{\operatorname{Math.abs}(x)}} = {|x|} = \begin{cases} x & \text{if} \quad x \geq 0 \\ x & \text{if} \quad x < 0 \end{cases}

語法

Math.abs(x)

參數

x
一個數字。

回傳值

給定數字的絕對值。

描述

Because abs() is a static method of Math, you always use it as Math.abs(), rather than as a method of a Math object you created (Math is not a constructor).

範例

Math.abs() 的行為

Passing an empty object, an array with more than one member, a non-numeric string or undefined/empty variable returns NaN. Passing null, an empty string or an empty array returns 0.

Math.abs('-1');     // 1
Math.abs(-2);       // 2
Math.abs(null);     // 0
Math.abs('');       // 0
Math.abs([]);       // 0
Math.abs([2]);      // 2
Math.abs([1,2]);    // NaN
Math.abs({});       // NaN
Math.abs('string'); // NaN
Math.abs();         // NaN

規範

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參見