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# Write File [![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] > Write data to a file.
## Installation ```bash npm install @stdlib/fs-write-file ```
## Usage ```javascript var writeFile = require( '@stdlib/fs-write-file' ); ``` #### writeFile( file, data\[, options], clbk ) Asynchronously writes `data` to a `file`. ```javascript var join = require( 'path' ).join; var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' ); writeFile( fpath, 'beep boop\n', onWrite ); function onWrite( error ) { if ( error ) { throw error; } } ``` The `data` argument may be either a `string` or a [`Buffer`][@stdlib/buffer/ctor]. ```javascript var join = require( 'path' ).join; var string2buffer = require( '@stdlib/buffer-from-string' ); var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' ); writeFile( fpath, string2buffer( 'beep boop\n' ), onWrite ); function onWrite( error ) { if ( error ) { throw error; } } ``` The function accepts the same `options` and has the same defaults as [`fs.writeFile()`][node-fs]. #### writeFile.sync( file, data\[, options] ) Synchronously writes `data` to a `file`. ```javascript var join = require( 'path' ).join; var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' ); var err = writeFile.sync( fpath, 'beep boop\n' ); if ( err instanceof Error ) { throw err; } ``` The function accepts the same `options` and has the same defaults as [`fs.writeFileSync()`][node-fs].
## Notes - The difference between this `writeFile.sync` and [`fs.writeFileSync()`][node-fs] is that [`fs.writeFileSync()`][node-fs] will throw if an `error` is encountered (e.g., if given a non-existent directory path) and this API will return an `error`. Hence, the following anti-pattern ```javascript var fs = require( 'fs' ); // Check for directory path existence to prevent an error being thrown... if ( fs.existsSync( '/path/to' ) ) { fs.writeFileSync( '/path/to/file.txt', 'beep boop\n' ); } ``` can be replaced by an approach which addresses existence via `error` handling. ```javascript var writeFile = require( '@stdlib/fs-write-file' ); // Explicitly handle the error... var err = writeFile.sync( '/path/to/file.txt', 'beep boop\n' ); if ( err instanceof Error ) { // You choose what to do... throw err; } ```
## Examples ```javascript var join = require( 'path' ).join; var writeFile = require( '@stdlib/fs-write-file' ); var fpath = join( __dirname, 'examples', 'fixtures', 'file.txt' ); // Synchronously write data to a file: var err = writeFile.sync( fpath, 'beep boop\n', 'utf8' ); // returns null console.log( err instanceof Error ); // => false // Asynchronously write data to a file: writeFile( fpath, 'beep boop\n', onWrite ); function onWrite( error ) { if ( error ) { console.error( 'Error: %s', error.message ); } console.log( 'Success!' ); } ```
## See Also - [`@stdlib/fs-write-file-cli`][@stdlib/fs-write-file-cli]: CLI package for use as a command-line utility. - [`@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.
* * * ## 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 © 2016-2026. The Stdlib [Authors][stdlib-authors].
[@stdlib/fs-write-file-cli]: https://www.npmjs.com/package/@stdlib/fs-write-file-cli [npm-image]: http://img.shields.io/npm/v/@stdlib/fs-write-file.svg [npm-url]: https://npmjs.org/package/@stdlib/fs-write-file [test-image]: https://github.com/stdlib-js/fs-write-file/actions/workflows/test.yml/badge.svg?branch=v0.2.3 [test-url]: https://github.com/stdlib-js/fs-write-file/actions/workflows/test.yml?query=branch:v0.2.3 [coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/fs-write-file/main.svg [coverage-url]: https://codecov.io/github/stdlib-js/fs-write-file?branch=main [chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg [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-write-file#cli [cli-url]: https://github.com/stdlib-js/fs-write-file/tree/cli [@stdlib/fs-write-file]: https://github.com/stdlib-js/fs-write-file/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-write-file/tree/deno [deno-readme]: https://github.com/stdlib-js/fs-write-file/blob/deno/README.md [umd-url]: https://github.com/stdlib-js/fs-write-file/tree/umd [umd-readme]: https://github.com/stdlib-js/fs-write-file/blob/umd/README.md [esm-url]: https://github.com/stdlib-js/fs-write-file/tree/esm [esm-readme]: https://github.com/stdlib-js/fs-write-file/blob/esm/README.md [branches-url]: https://github.com/stdlib-js/fs-write-file/blob/main/branches.md [stdlib-license]: https://raw.githubusercontent.com/stdlib-js/fs-write-file/main/LICENSE [node-fs]: https://nodejs.org/api/fs.html [@stdlib/buffer/ctor]: https://www.npmjs.com/package/@stdlib/buffer-ctor [standard-stream]: https://en.wikipedia.org/wiki/Pipeline_%28Unix%29 [@stdlib/fs/exists]: https://www.npmjs.com/package/@stdlib/fs-exists [@stdlib/fs/read-file]: https://www.npmjs.com/package/@stdlib/fs-read-file