JavaScript Number isNaN() Method
Example
Check whether a value is NaN:
Number.isNaN(123) //false
Number.isNaN(-1.23) //false
Number.isNaN(5-2)
//false
Number.isNaN(0) //false
Number.isNaN('123') //false
Number.isNaN('Hello')
//false
Number.isNaN('2005/12/12') //false
Number.isNaN('') //false
Number.isNaN(true)
//false
Number.isNaN(undefined) //false
Number.isNaN('NaN') //false
Number.isNaN(NaN)
//true
Number.isNaN(0 / 0) //true
Try it yourself »
Definition and Usage
The Number.isNaN() method determines whether a value is NaN (Not-A-Number).
This method returns true if the value is of the type Number, and equates to NaN. Otherwise it returns false.
Number.isNaN() is different from the global isNaN() function. The global isNaN() function converts the tested value to a Number, then tests it.
Number.isNan() does not convert the values to a Number, and will not return true for any value that is not of the type Number.
Tip: In JavaScript, the value NaN is considered a type of number.
Browser Support
| Method | ||||||
|---|---|---|---|---|---|---|
| Number.isNaN() | Yes | 12.0 | No | 32 | 9 | 22 |
Note: The Number.isNaN() method is not supported in Internet Explorer 11 and earlier versions.
Syntax
Number.isNaN(value)
Parameter Values
| Parameter | Description |
|---|---|
| value | Required. The value to be tested |
Technical Details
| Return Value: | A Boolean. Returns true if the value is Number.NaN, otherwise it returns false |
|---|---|
| JavaScript Version: | ECMAScript 6 |
JavaScript Number Reference
