Math.abs()

Math.abs() 函式會回傳一個數字的絕對值，即為：

$${\mathtt{\operatorname{Math.abs}(x)}} = {|x|} = \begin{cases} x & \text{if} \quad x \geq 0 \\ x & \text{if} \quad x < 0 \end{cases}$$

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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

瀏覽器相容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

參見

• Math.ceil()
• Math.floor()
• Math.round()
• Math.sign()
• Math.trunc()