JavaScript Number isNaN() Method

　JavaScript Number Object

isNaN()Method determines whether the passed value is NaN (Not-A-Number).

If the type of the value is Number, this method returns true and equals NaN; otherwise, it returns false.

This method is different from the globalisNaN()Function.

GlobalisNaN()Function, which converts the tested value to Number and then tests it.

Number.isNaN() does not convert the value to Number and will not return true for any non-Number type values.

Syntax:

Number.isNaN(value)

Number.isNaN(451);　　　//　false
Number.isNaN(-3.13);　//　false
Number.isNaN(3-1);　　　//　false
Number.isNaN(0);　//　false
Number.isNaN("451);　//　false
Number.isNaN("Hello");　　　//　false
Number.isNaN("20/12/2018);　　//　false
Number.isNaN(&39&;39;);//　false
Number.isNaN(true);　　//　false
Number.isNaN(undefined);　//　false
Number.isNaN(&39;NaN&39;);　//　false
Number.isNaN(NaN);　　　//　true
Number.isNaN(0　/　0);　//　true

Browser Compatibility

The numbers in the table specify the first browser version that fully supports the isNaN() method:

Parameter Value

Technical Details

　JavaScript Number Object