Zero and Minus Zero in JavaScript

In JavaScript, there are 2 different zeros. A regular 0 is a bit different from -0 in JS.

If you divide a zero by any negative number, you’ll get -0.

The only reason why minus zero exists in JS is the fact that JavaScript implements the IEEE Standard for Floating-Point Arithmetic (IEEE 754), which has signed zeroes.

Let’s take a look at how 0 and -0 look like when logged to the console and how these values compare to each other.

const zero = 0;
const minusZero = zero / -1;

console.log(zero);      // 0
console.log(minusZero); // -0

console.log(zero === minusZero); // true

As you see, even though 0 and -0 appear differently when logged to the console, they appear equal when compared using the strict equality operator.

If you need a function that would tell the explicit difference between 0 and -0 in JavaScript, you can use Object.is.

Object.is(-0, +0); // false