Test if a value is NaN.
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> Test if a value is NaN.
``bash`
npm install @stdlib/assert-is-nan
`javascript`
var isnan = require( '@stdlib/assert-is-nan' );
#### isnan( value )
Tests if a value is NaN.
`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.
`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.
`javascript
var Number = require( '@stdlib/number-ctor' );
var bool = isnan.isObject( NaN );
// returns false
bool = isnan.isObject( new Number( NaN ) );
// returns true
`
`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
`
*
- [@stdlib/assert-is-number][@stdlib/assert/is-number]: test if a value is a number.
*
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].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[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
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[@stdlib/assert/is-number]: https://www.npmjs.com/package/@stdlib/assert-is-number