 # Check if number is not greater than 0 in JavaScript Fortunately, there are already many functions that can check if number is not greater than 0 in JavaScript. We will discover how to do it using two different ways, namely Math.sign() and <= operator. Each approach is straightforward, so you can use whichever you want.

## Check if number is not greater than 0 in JavaScript

### Using Math.sign()

Syntax:

Math.sign(value)

Parameter:

• value: The value to check can be a string or a number.

The Math.sign() function answers whether a number is not greater than 0 by the returned value. If the returned value is 1, then it is greater than 0. Otherwise, the returned value is 0 or -1 indicates that the number is not greater than 0. For example:

// Check the sign of a number
let num = "-2022";
console.log(Math.sign(num));

// Check the sign of a number
num = "0";
console.log(Math.sign(num));

Output:

-1
0

As can be seen in the above example. We didn’t pass a number but instead a string that represents the number, but the method still works fine as it has converted them into numbers for you when returning the result. As there is a zero number in our example, the method will return 0. Therefore, we can check if a number is not greater than 0 by checking if the output is not 1:

// Check if number is not greater than 0 in JavaScript
let num = "-2022";

if (Math.sign(num) != 1) {
console.log(num + " is not greater than 0");
} else {
console.log(num + " is greater than 0");
}

Output:

-2022 is not greater than 0

Another example:

// Check if number is not greater than 0 in JavaScript
let num = 0;

if (Math.sign(num) != 1) {
console.log(num + " is not greater than 0");
} else {
console.log(num + " is greater than 0");
}

Result:

0 is not greater than 0

### Using binary <= operator

Syntax:

value <= 0

Parameter:

• value: The value to be checked (a number or numeric string).

We have learned in mathematics that any number not greater than zero can be a zero number or a negative number, which is smaller than zero. Therefore, we should use the smaller than or equal to (<=) operator to check if number is not greater than 0. For example:

// Check if number is not greater than 0 in JavaScript
let num = 0;

if (num <= 0) {
console.log(num + " is not greater than 0");
} else {
console.log(num + " is greater than 0");
}

Output:

0 is not greater than 0


Another example:

// Check if number is not greater than 0 in JavaScript
let num = 1;

if (num <= 0) {
console.log(num + " is not greater than 0");
} else {
console.log(num + " is greater than 0");
}

Output:

1 is greater than 0

As can be seen, this approach not only produces the expected results as the first one but is also easy for everyone as it is a math operator that has been taught many times in school. It is the fact that most programmers are likely to use this way more than other ways. Furthermore, there are also some other ways to solve this problem, but we don’t recommend you use them as these methods introduced in this article are the best ones.

## Summary

We have found out how to check if number is not greater than 0 in JavaScript using two different methods. Although there are more ways to do this, we suggest you use the binary <= operator because it is the quickest method.

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