About stdlib...

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The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

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isString

Test if a value is a string.

Installation

npm install @stdlib/assert-is-string

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var isString = require( '@stdlib/assert-is-string' );

isString( value )

Tests if a value is a string.

var bool = isString( 'beep' );
// returns true

bool = isString( new String( 'beep' ) );
// returns true

isString.isPrimitive( value )

Tests if a value is a primitive string.

var bool = isString.isPrimitive( 'beep' );
// returns true

bool = isString.isPrimitive( new String( 'boop' ) );
// returns false

isString.isObject( value )

Tests if a value is a String object.

var bool = isString.isObject( 'beep' );
// returns false

bool = isString.isObject( new String( 'boop' ) );
// returns true

Examples

var isString = require( '@stdlib/assert-is-string' );

var bool = isString( 'beep' );
// returns true

bool = isString( new String( 'beep' ) );
// returns true

bool = isString( 5 );
// returns false

bool = isString( null );
// returns false

bool = isString( void 0 );
// returns false

bool = isString( {} );
// returns false

bool = isString( [] );
// returns false

bool = isString( function foo() {} );
// returns false

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Notice

This package is part of 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, see the main project repository.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.