Get the absolute value of a number in Javascript

Question

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 = Math.sqrt(x) console.log(x)

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

Answer 1

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  console.log(x);

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 

Answer 2

Here is a fast way to obtain the absolute value of a number. It's applicable on every language:

x = -25; console.log((x ^ (x >> 31)) - (x >> 31));