npm package: @stdlib/assert-is-nan
Description: Test if a value is NaN.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
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</details>

# isNaN

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Test if a value is NaN.

<section class="installation">

## Installation

```bash
npm install @stdlib/assert-is-nan
```

</section>

<section class="usage">

## Usage

```javascript
var isnan = require( '@stdlib/assert-is-nan' );
```

#### isnan( value )

Tests if a `value` is `NaN`.

<!-- eslint-disable no-new-wrappers -->

```javascript
var Number = require( '@stdlib/number-ctor' );

var bool = isnan( NaN );
// returns true

bool = isnan( new Number( NaN ) );
// returns true

bool = isnan( 3.14 );
// returns false

bool = isnan( null );
// returns false
```

#### isnan.isPrimitive( value )

Tests if a `value` is a `NaN` primitive `number`.

<!-- eslint-disable no-new-wrappers -->

```javascript
var Number = require( '@stdlib/number-ctor' );

var bool = isnan.isPrimitive( NaN );
// returns true

bool = isnan.isPrimitive( 3.14 );
// returns false

bool = isnan.isPrimitive( new Number( NaN ) );
// returns false
```

#### isnan.isObject( value )

Tests if a `value` is a `Number` object having a value of `NaN`.

<!-- eslint-disable no-new-wrappers -->

```javascript
var Number = require( '@stdlib/number-ctor' );

var bool = isnan.isObject( NaN );
// returns false

bool = isnan.isObject( new Number( NaN ) );
// returns true
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- eslint-disable no-new-wrappers -->

<!-- eslint no-undef: "error" -->

```javascript
var Number = require( '@stdlib/number-ctor' );
var Symbol = require( '@stdlib/symbol-ctor' );
var isnan = require( '@stdlib/assert-is-nan' );

var bool = isnan( NaN );
// returns true

bool = isnan( new Number( NaN ) );
// returns true

bool = isnan( 5 );
// returns false

bool = isnan( '5' );
// returns false

bool = isnan( null );
// returns false

bool = isnan( Symbol( 'NaN' ) );
// returns false
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/assert-is-number`][@stdlib/assert/is-number]</span><span class="delimiter">: </span><span class="description">test if a value is a number.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->


<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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<section class="links">

[npm-image]: http://img.shields.io/npm/v/@stdlib/assert-is-nan.svg
[npm-url]: https://npmjs.org/package/@stdlib/assert-is-nan

[test-image]: https://github.com/stdlib-js/assert-is-nan/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/assert-is-nan/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/assert-is-nan/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/assert-is-nan?branch=main

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[stdlib]: https://github.com/stdlib-js/stdlib

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/assert-is-nan/tree/deno
[deno-readme]: https://github.com/stdlib-js/assert-is-nan/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/assert-is-nan/tree/umd
[umd-readme]: https://github.com/stdlib-js/assert-is-nan/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/assert-is-nan/tree/esm
[esm-readme]: https://github.com/stdlib-js/assert-is-nan/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/assert-is-nan/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/assert-is-nan/main/LICENSE

<!-- <related-links> -->

[@stdlib/assert/is-number]: https://www.npmjs.com/package/@stdlib/assert-is-number

<!-- </related-links> -->

</section>

<!-- /.links -->