Open a file.
npm install @stdlib/fs-openWe 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!
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> Open a file.
``bash`
npm install @stdlib/fs-open
`javascript`
var open = require( '@stdlib/fs-open' );
#### open( path\[, flags\[, mode]], clbk )
Asynchronously opens a file.
`javascript
var closeSync = require( '@stdlib/fs-close' ).sync;
open( __filename, onOpen );
function onOpen( error, fd ) {
if ( error ) {
console.error( error.message );
} else {
closeSync( fd );
}
}
`
The function has the same default parameter values as [fs.open()][node-fs].
#### open.sync( file\[, flags\[, mode]] )
Synchronously opens a file.
`javascript
var closeSync = require( '@stdlib/fs-close' ).sync;
var fd = open.sync( __filename );
if ( fd instanceof Error ) {
console.error( fd.message );
} else {
closeSync( fd );
}
`
The function has the same default parameters as [fs.openSync()][node-fs].
- The difference between this API and [fs.openSync()][node-fs] is that [fs.openSync()][node-fs] will throw if an error is encountered (e.g., if given a non-existent path) and this API will return an error. Hence, the following anti-pattern
`javascript
var fs = require( 'fs' );
var fpath = '/path/to/file.js';
var fd;
// Check for existence to prevent an error being thrown...
if ( fs.existsSync( fpath ) ) {
fd = fs.readFileSync( fpath );
}
`
can be replaced by an approach which addresses existence via error handling.
`javascript
var open = require( '@stdlib/fs-open' );
var fpath = '/path/to/file.js';
// Explicitly handle the error...
var fd = open.sync( fpath );
if ( fd instanceof Error ) {
// You choose what to do...
console.error( fd.message );
}
`
`javascript
var join = require( 'path' ).join;
var closeSync = require( '@stdlib/fs-close' ).sync;
var open = require( '@stdlib/fs-open' );
/ Sync /
var fd = open.sync( join( __dirname, 'package.json' ), 'r+' );
// returns
if ( fd instanceof Error ) {
console.error( fd.message );
} else {
closeSync( fd );
}
fd = open.sync( 'beepboop' );
// returns
/ Async /
open( join( __dirname, 'package.json' ), onOpen );
open( 'beepboop', onOpen );
function onOpen( error, fd ) {
if ( error ) {
if ( error.code === 'ENOENT' ) {
console.error( 'File does not exist.' );
} else {
console.error( error.message );
}
} else {
closeSync( fd );
}
}
`
*
- [@stdlib/fs-close][@stdlib/fs/close]: close a file descriptor.
- [@stdlib/fs-exists][@stdlib/fs/exists]: test whether a path exists on the filesystem.
- [@stdlib/fs-read-file][@stdlib/fs/read-file]: read the entire contents of a file.
*
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]
---
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/fs-open/tree/deno
[deno-readme]: https://github.com/stdlib-js/fs-open/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/fs-open/tree/umd
[umd-readme]: https://github.com/stdlib-js/fs-open/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/fs-open/tree/esm
[esm-readme]: https://github.com/stdlib-js/fs-open/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/fs-open/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/fs-open/main/LICENSE
[node-fs]: https://nodejs.org/api/fs.html
[@stdlib/fs/close]: https://www.npmjs.com/package/@stdlib/fs-close
[@stdlib/fs/exists]: https://www.npmjs.com/package/@stdlib/fs-exists
[@stdlib/fs/read-file]: https://www.npmjs.com/package/@stdlib/fs-read-file