@stdlib/fs/open/README.md

Filesystem APIs.

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# Open

> Open a file.

<section class="usage">

## Usage

<!-- eslint-disable stdlib/no-redeclare -->

```javascript
var open = require( '@stdlib/fs/open' );
```

#### open( path\[, flags\[, mode]], clbk )

Asynchronously opens a file.

<!-- eslint-disable stdlib/no-redeclare -->

```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`.

<!-- eslint-disable stdlib/no-redeclare -->

```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].

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   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

    <!-- eslint-disable stdlib/no-redeclare -->

    ```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.

    <!-- eslint-disable stdlib/no-redeclare -->

    ```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 );
    }
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint-disable stdlib/no-redeclare -->

<!-- eslint no-undef: "error" -->

```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 <number>

if ( fd instanceof Error ) {
    console.error( fd.message );
} else {
    closeSync( fd );
}

fd = open.sync( 'beepboop' );
// returns <Error>

/* 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 );
    }
}
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/fs/close`][@stdlib/fs/close]</span><span class="delimiter">: </span><span class="description">close a file descriptor.</span>
-   <span class="package-name">[`@stdlib/fs/exists`][@stdlib/fs/exists]</span><span class="delimiter">: </span><span class="description">test whether a path exists on the filesystem.</span>
-   <span class="package-name">[`@stdlib/fs/read-file`][@stdlib/fs/read-file]</span><span class="delimiter">: </span><span class="description">read the entire contents of a file.</span>

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[node-fs]: https://nodejs.org/api/fs.html

<!-- <related-links> -->

[@stdlib/fs/close]: https://github.com/stdlib-js/fs/tree/main/close

[@stdlib/fs/exists]: https://github.com/stdlib-js/fs/tree/main/exists

[@stdlib/fs/read-file]: https://github.com/stdlib-js/fs/tree/main/read-file

<!-- </related-links> -->

</section>

<!-- /.links -->