Math.abs()
函式會回傳一個數字的絕對值,即為:
The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.
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
Specification | Status | Comment |
---|---|---|
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.0. |
ECMAScript 5.1 (ECMA-262) The definition of 'Math.abs' in that specification. |
Standard | |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Math.abs' in that specification. |
Standard | |
ECMAScript (ECMA-262) The definition of 'Math.abs' in that specification. |
Living Standard |
瀏覽器相容性
BCD tables only load in the browser
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.