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JavaScript Number isNaN()

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Examples

Check if a value is Number.NaN:

Number.isNaN(123);
Number.isNaN(-1.23);
Number.isNaN('123');
Number.isNaN(0/0);
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Number.isNaN(5-2);
Number.isNaN(0);
Number.isNaN('Hello');
Number.isNaN('2005/12/12');
Number.isNaN(' ');
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More examples below.

Description

In JavaScript, NaN is short for "Not-a-Number".

In JavaScript, NaN is a number that is not a legal number.

The Number.isNaN() method returns true if the value is NaN, and the type is a Number.

See Also:

The NaN() Property

The Global isNaN() Method

Difference Between isnan() and Number.isnan()

isNaN() method returns true if a value is Not-a-Number.

Number.isNaN() returns true if a number is Not-a-Number.

In other words:

isNaN() converts the value to a number before testing it.

Examples

// This returns true;
isNaN('Hello');
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// This returns false;
Number.isNaN('Hello');
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Syntax

Number.isNaN( value)

Parameters

Parameter Description
value Required.
The value to be tested.

Return Value

Type Description
A boolean. true if the value is Number.NaN, otherwise false.

More Examples

Check if a value is Number.NaN:

Number.isNaN(false);
Number.isNaN(true);
Number.isNaN(undefined);
Number.isNaN('NaN');
Number.isNaN(NaN);
Try it Yourself »

Browser Support

Number.isNaN() is an ECMAScript6 (ES6) feature.

ES6 (JavaScript 2015) is supported in all modern browsers:

Chrome Edge Firefox Safari Opera
Yes Yes Yes Yes Yes

Number.isNaN() is not supported in Internet Explorer 11 (or earlier).

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