negativeZeroComparisons

Reports comparisons with -0 that may not behave as expected.

✅ This rule is included in the ts logical and logicalStrict presets.

In JavaScript, -0 and +0 are distinct values, but standard comparison operators (===, ==, !==, !=, <, <=, >, >=) treat them as equal. This can lead to unexpected behavior when you need to distinguish between these values.

The Object.is() method correctly distinguishes between -0 and +0, making it the reliable choice when checking for negative zero.

function 
function checkValue(value: number): "negative zero" | "other"
checkValue(
value: number
value: number) {
  if (
value: number
value === -0) {
    return "negative zero";
  }
  return "other";
}

// Also incorrect with other operators
if (
const value: number
value == -0) {
}
if (
const value: number
value !== -0) {
}
if (
const value: number
value < -0) {
}
if (
const value: number
value >= -0) {
}

function 
function checkValue(value: number): "negative zero" | "other"
checkValue(
value: number
value: number) {
  if (
var Object: ObjectConstructor
Provides functionality common to all JavaScript objects.
Object.
ObjectConstructor.is(value1: any, value2: any): boolean
Returns true if the values are the same value, false otherwise.
@param ― value1 The first value.
@param ― value2 The second value.
is(
value: number
value, -0)) {
    return "negative zero";
  }
  return "other";
}

// Regular zero comparisons are fine
if (
const value: number
value === 0) {
}

// Negative one and other numbers are fine
if (
const value: number
value === -1) {
}

// Using -0 in non-comparison contexts is fine
const 
const negativeZero: 0
negativeZero = -0;
const 
const result: number
result = -0 + 1;

Options

This rule is not configurable.

When Not To Use It

If you never need to distinguish between -0 and +0 in your codebase, you might choose to disable this rule. However, keeping it enabled helps prevent subtle bugs where the distinction matters, such as when working with mathematical calculations that produce negative zero (e.g., -1 / Infinity results in -0).

Equivalents in Other Linters

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negativeZeroComparisons

Examples

Options

When Not To Use It

Further Reading

Equivalents in Other Linters