在Javascript中获取数字的绝对值 [英] Get the absolute value of a number in Javascript

问题描述

我想在JavaScript中获取数字的绝对值。也就是说，放下标志。
我在数学上知道我可以通过平方数然后取平方根来做到这一点，但我也知道这非常低效。

I want to get the absolute value of a number in JavaScript. That is, drop the sign. I know mathematically I can do this by squaring the number then taking the square root, but I also know that this is horribly inefficient.

x = -25
x = x * x 
x = sqrt(x)

// x would now be 25 

JavaScript中有没有办法简单地删除标志一个比数学方法更有效的数字？

Is there a way in JavaScript to simply drop the sign of a number that is more efficient than the mathematical approach?

推荐答案

你的意思是得到一个数字的绝对值？ Math.abs javascript函数专为此目的而设计。

You mean like getting the absolute value of a number? The Math.abs javascript function is designed exactly for this purpose.

var x = -25;
x = Math.abs(x); // x would now be 25 

以下是文档中的一些测试用例：

Here are some test cases from the documentation:

Math.abs('-1');     // 1
Math.abs(-2);       // 2
Math.abs(null);     // 0
Math.abs("string"); // NaN
Math.abs();         // NaN

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