# JavaScript Number NaN Property

Last Updated : 22 May, 2023

In JavaScript, NaN stands for Not a Number. It represents a value that is not a valid number. It can be used to check whether a number entered is a valid number or not a number. To assign a variable to NaN value, we can use one of the two following ways.

Syntax:

```let a = NaN
// OR
let a = Number.NaN```

Example 1: In this example, we will use JavaScript Number NaN Property.

## javascript

 `let monthNumber = 14;`   `if` `(monthNumber < 1 || monthNumber > 12) {`   `    ``// Assigning monthNumber NaN as` `    ``// month number is not valid` `    ``monthNumber = Number.NaN;`   `    ``console.log(``"Month number should be"` `                ``+ ``" between 1 and 12"``);` `}` `else` `{` `    ``console.log(monthNumber);` `}`

Output:

`Month number should be between 1 and 12`

Example 2: Whenever we try to parse a string or “undefined” to an int, it returns NaN.

## javascript

 `console.log(parseInt(``"higeeks"``));`

Output:

`Nan`

Example 3: Whenever we try to find square root of a negative number using Math.sqrt function, it returns NaN.

## javascript

 `console.log(Math.sqrt(-1));`

Output:

`NaN`

Example 4: Whenever we try to make on operation on NaN, it returns NaN.

## javascript

 `console.log(5 + NaN);`

Output:

`NaN`

Example 5: Any indeterminate form also returns NaN.

## javascript

 `console.log(0 * Infinity)`

Output:

`NaN`

Example 6: Any operation other than addition on a string also results in NaN.

## javascript

 `console.log(``"hi"``/5)`

Output:

`NaN`

Supported Browser:

• Chrome 1 and above
• Edge 12 and above
• Firefox 1 and above
• Internet Explorer 4 and above
• Opera 3 and above
• Safari 1 and above

We have a Cheat Sheet on Javascript Numbers where we covered all the important topics of Javascript to check those please go through JavaScript Number Complete Reference.

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