177 lines
3.6 KiB
Markdown
177 lines
3.6 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2019 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# Open
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> Open a file.
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<section class="usage">
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## Usage
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<!-- eslint-disable stdlib/no-redeclare -->
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```javascript
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var open = require( '@stdlib/fs/open' );
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```
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#### open( path\[, flags\[, mode]], clbk )
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Asynchronously opens a file.
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<!-- eslint-disable stdlib/no-redeclare -->
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```javascript
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var closeSync = require( '@stdlib/fs/close' ).sync;
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open( __filename, onOpen );
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function onOpen( error, fd ) {
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if ( error ) {
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console.error( error.message );
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} else {
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closeSync( fd );
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}
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}
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```
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The function has the same default parameter values as [`fs.open()`][node-fs].
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#### open.sync( file\[, flags\[, mode]] )
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Synchronously opens a `file`.
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<!-- eslint-disable stdlib/no-redeclare -->
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```javascript
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var closeSync = require( '@stdlib/fs/close' ).sync;
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var fd = open.sync( __filename );
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if ( fd instanceof Error ) {
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console.error( fd.message );
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} else {
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closeSync( fd );
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}
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```
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The function has the same default parameters as [`fs.openSync()`][node-fs].
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- 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
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<!-- eslint-disable stdlib/no-redeclare -->
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```javascript
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var fs = require( 'fs' );
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var fpath = '/path/to/file.js';
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var fd;
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// Check for existence to prevent an error being thrown...
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if ( fs.existsSync( fpath ) ) {
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fd = fs.readFileSync( fpath );
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}
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```
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can be replaced by an approach which addresses existence via `error` handling.
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<!-- eslint-disable stdlib/no-redeclare -->
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```javascript
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var open = require( '@stdlib/fs/open' );
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var fpath = '/path/to/file.js';
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// Explicitly handle the error...
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var fd = open.sync( fpath );
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if ( fd instanceof Error ) {
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// You choose what to do...
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console.error( fd.message );
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}
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```
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint-disable stdlib/no-redeclare -->
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<!-- eslint no-undef: "error" -->
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```javascript
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var join = require( 'path' ).join;
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var closeSync = require( '@stdlib/fs/close' ).sync;
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var open = require( '@stdlib/fs/open' );
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/* Sync */
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var fd = open.sync( join( __dirname, 'package.json' ), 'r+' );
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// returns <number>
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if ( fd instanceof Error ) {
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console.error( fd.message );
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} else {
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closeSync( fd );
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}
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fd = open.sync( 'beepboop' );
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// returns <Error>
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/* Async */
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open( join( __dirname, 'package.json' ), onOpen );
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open( 'beepboop', onOpen );
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function onOpen( error, fd ) {
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if ( error ) {
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if ( error.code === 'ENOENT' ) {
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console.error( 'File does not exist.' );
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} else {
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console.error( error.message );
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}
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} else {
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closeSync( fd );
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}
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}
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[node-fs]: https://nodejs.org/api/fs.html
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</section>
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<!-- /.links -->
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