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https://github.com/stdlib-js/fs-exists
Test whether a path exists on the filesystem.
https://github.com/stdlib-js/fs-exists
async check existence exists existssync file filesystem fs javascript node node-js nodejs path polyfill stdlib sync
Last synced: 11 days ago
JSON representation
Test whether a path exists on the filesystem.
- Host: GitHub
- URL: https://github.com/stdlib-js/fs-exists
- Owner: stdlib-js
- License: apache-2.0
- Created: 2021-06-13T19:16:02.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2024-10-01T01:48:21.000Z (about 1 month ago)
- Last Synced: 2024-10-26T02:31:38.393Z (18 days ago)
- Topics: async, check, existence, exists, existssync, file, filesystem, fs, javascript, node, node-js, nodejs, path, polyfill, stdlib, sync
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 553 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
Awesome Lists containing this project
README
About stdlib...
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.
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.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
# Exists
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Test whether a path exists on the filesystem.
## Installation
```bash
npm install @stdlib/fs-exists
```
Alternatively,
- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).
- To use as a general utility for the command line, install the corresponding [CLI package][cli-section] globally.
The [branches.md][branches-url] 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
```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
```
## Notes
- 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'
});
}
```
## Examples
```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 );
}
}
```
* * *
## CLI
## Installation
To use as a general utility, install the CLI package globally
```bash
npm install -g @stdlib/fs-exists-cli
```
### Usage
```text
Usage: exists [options]
Options:
-h, --help Print this message.
-V, --version Print the package version.
```
### Notes
- Relative paths are resolved relative to the current working directory.
- Errors are written to `stderr`.
- Results are written to `stdout`.
### Examples
```bash
$ exists ./../
true ||
```
* * *
## See Also
- [`@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.
* * *
## 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 © 2016-2024. The Stdlib [Authors][stdlib-authors].
[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=main
[test-url]: https://github.com/stdlib-js/fs-exists/actions/workflows/test.yml?query=branch:main
[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
[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg
[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im
[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://github.com/stdlib-js/fs-read-file
[@stdlib/fs/read-dir]: https://github.com/stdlib-js/fs-read-dir