Test whether a path exists on the filesystem.
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> Test whether a path exists on the filesystem.
``bash`
npm install @stdlib/fs-exists
`javascript`
var exists = require( '@stdlib/fs-exists' );
#### exists( path, clbk )
Asynchronously tests whether a path exists on the filesystem.
`javascript
exists( __dirname, done );
function done( bool ) {
if ( bool ) {
console.log( '...path exists.' );
} else {
console.log( '...path does not exist.' );
}
}
`
The above callback signature matches the now deprecated [fs.exists()][node-fs-exists] API. The function also accepts the more conventional error-first style callback signature found in most asynchronous Node APIs.
`javascript
exists( __dirname, done );
function done( error, bool ) {
if ( error ) {
console.error( error.message );
}
if ( bool ) {
console.log( '...path exists.' );
} else {
console.log( '...path does not exist.' );
}
}
`
#### exists.sync( path )
Synchronously tests whether a path exists on the filesystem.
`javascript`
var bool = exists.sync( __dirname );
// returns
- The following is considered an anti-pattern:
`javascript
var path = require( 'path' );
var readFileSync = require( '@stdlib/fs-read-file' ).sync;
var file = path.join( __dirname, 'foo.js' );
if ( exists.sync( __dirname ) ) {
file = readFileSync( file );
}
`
Because time elapses between checking for existence and performing IO, at the time IO is performed, the path is no longer guaranteed to exist. In other words, a race condition exists between the process attempting to read and another process attempting to delete.
Instead, the following pattern is preferred, where errors are handled explicitly:
`javascript
var path = require( 'path' );
var readFileSync = require( '@stdlib/fs-read-file' ).sync;
var file = path.join( __dirname, 'foo.js' );
try {
file = readFileSync( file );
} catch ( error ) {
console.log( 'unable to read file.' );
console.error( error );
}
`
- Nevertheless, use cases exist where one desires to check existence without performing IO. For example,
`javascript
var path = require( 'path' );
var writeFileSync = require( '@stdlib/fs-write-file' ).sync;
var file = path.join( __dirname, 'foo.js' );
if ( exists.sync( file ) ) {
console.log( 'Don\'t overwrite the file!' );
} else {
writeFileSync( file, 'beep', {
'encoding': 'utf8'
});
}
`
`javascript
var exists = require( '@stdlib/fs-exists' );
/ Sync /
console.log( exists.sync( __dirname ) );
// => true
console.log( exists.sync( 'beepboop' ) );
// => false
/ Async /
exists( __dirname, done );
exists( 'beepboop', done );
function done( error, bool ) {
if ( error ) {
console.error( error.message );
} else {
console.log( bool );
}
}
`
- [@stdlib/fs-exists-cli][@stdlib/fs-exists-cli]: CLI package for use as a command-line utility.
- [@stdlib/fs-read-file][@stdlib/fs/read-file]: read the entire contents of a file.
- [@stdlib/fs-read-dir][@stdlib/fs/read-dir]: read the entire contents of a directory.
*
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].
[@stdlib/fs-exists-cli]: https://www.npmjs.com/package/@stdlib/fs-exists-cli
[npm-image]: http://img.shields.io/npm/v/@stdlib/fs-exists.svg
[npm-url]: https://npmjs.org/package/@stdlib/fs-exists
[test-image]: https://github.com/stdlib-js/fs-exists/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/fs-exists/actions/workflows/test.yml?query=branch:v0.2.3
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/fs-exists/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/fs-exists?branch=main
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[chat-url]: https://stdlib.zulipchat.com
[stdlib]: https://github.com/stdlib-js/stdlib
[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors
[cli-section]: https://github.com/stdlib-js/fs-exists#cli
[cli-url]: https://github.com/stdlib-js/fs-exists/tree/cli
[@stdlib/fs-exists]: https://github.com/stdlib-js/fs-exists/tree/main
[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/fs-exists/tree/deno
[deno-readme]: https://github.com/stdlib-js/fs-exists/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/fs-exists/tree/umd
[umd-readme]: https://github.com/stdlib-js/fs-exists/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/fs-exists/tree/esm
[esm-readme]: https://github.com/stdlib-js/fs-exists/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/fs-exists/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/fs-exists/main/LICENSE
[node-fs-exists]: https://nodejs.org/api/fs.html#fs_fs_exists_path_callback
[@stdlib/fs/read-file]: https://www.npmjs.com/package/@stdlib/fs-read-file
[@stdlib/fs/read-dir]: https://www.npmjs.com/package/@stdlib/fs-read-dir