Let’s see an example using both the methods.

## 1) Using Comparison Operator

<script> const number = -5; if (number < 0) document.write (number + ' is negetive'); else document.write (number + ' is positive'); </script>

In the above example, I am using the < (less than) operator to check if the number is either negative or positive.

Anybody can tell that the value is a negative number, just by looking at it, since I have assigned a negative value in the variable. **However**, you’ll need a condition like the one I have explained in the above example, when you are doing some big calculations and at runtime you need to check the value.

**Now**, guess what the above condition returns. Well, it returns a Boolean true or false. Do this to check…

<script> const number = -5; document.write (number < 0); </script>

The output is true, since it’s a negative value.

## 2) Using Math.sign()

You can use the Math.sign() function in JavaScript, to check if a number is negative or positive. This new ES6 method takes an argument in the form of a number. Here’s the syntax.

Math.sign(number)

The function will return either of this …

1, -1, 0, -0, or NaN

The function returns the **sign** of the number (not any value). Therefore, if it’s a positive number, it will return 1 and if the number is negative, it will -1. If the value is zero it will return 0.

**NaN** denotes Not a Number, in case the parameter (or the argument) is not a number.

**Note**: The function is case sensitive.

Now, let's see how the function works.

```
<script>
const number = 17;
let result = Math.sign(number) > 0 ? ' is positive' : ' is negative';
document.write (number + result);
</script>
```

Also, check the return type.

```
<script>
const number = 17;
document.write (Math.sign(number));
</script>
```

The output you should see is 1, that’s positive.

## Difference between Comparison Operator and Math.sign() function

The **difference** between using the Comparison Operator and Math.sign() function is that the former returns a Boolean value (true or false) and later returns the sign of the number (-1 or 1).

Let's see both the methods together.

```
<script>
const number = -5;
document.write (number < 0); // if its less than 0.
document.write (Math.sign(number));
</script>
```

## Examples using Math.sign()

Example | |
---|---|

1. | document.write (Math.sign()); Try it |

2. | const number = -5 - 10; document.write (Math.sign(number));Try it |

3. | const number = -15 + 12; document.write (Math.sign(number)); Try it |

Thanks for reading. ☺