time-to-botec/squiggle/node_modules/@stdlib/fs/read-file/README.md

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# Read File

> Read the entire contents of a file.

<section class="usage">

## Usage

```javascript
var readFile = require( '@stdlib/fs/read-file' );
```

#### readFile( file\[, options], clbk )

Asynchronously reads the entire contents of a file.

```javascript
readFile( __filename, onFile );

function onFile( error, data ) {
    if ( error ) {
        throw error;
    }
    console.log( data );
}
```

The function accepts the same `options` and has the same defaults as [`fs.readFile()`][node-fs].

#### readFile.sync( file\[, options] )

Synchronously reads the entire contents of a `file`.

```javascript
var out = readFile.sync( __filename );
if ( out instanceof Error ) {
    throw out;
}
console.log( out );
```

The function accepts the same `options` and has the same defaults as [`fs.readFileSync()`][node-fs].

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   The difference between this API and [`fs.readFileSync()`][node-fs] is that [`fs.readFileSync()`][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 file = '/path/to/file.js';

    // Check for existence to prevent an error being thrown...
    if ( fs.existsSync( file ) ) {
        file = fs.readFileSync( file );
    }
    ```

    can be replaced by an approach which addresses existence via `error` handling.

    ```javascript
    var readFile = require( '@stdlib/fs/read-file' );

    var file = '/path/to/file.js';

    // Explicitly handle the error...
    file = readFile.sync( file );
    if ( file instanceof Error ) {
        // You choose what to do...
        console.error( file.message );
    }
    ```

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var readFile = require( '@stdlib/fs/read-file' );

/* Sync */

var file = readFile.sync( __filename, 'utf8' );
// returns <string>

console.log( file instanceof Error );
// => false

file = readFile.sync( 'beepboop', {
    'encoding': 'utf8'
});
// returns <Error>

console.log( file instanceof Error );
// => true

/* Async */

readFile( __filename, onFile );
readFile( 'beepboop', onFile );

function onFile( error, data ) {
    if ( error ) {
        if ( error.code === 'ENOENT' ) {
            console.error( 'File does not exist.' );
        } else {
            throw error;
        }
    } else {
        console.log( data );
    }
}
```

</section>

<!-- /.examples -->

* * *

<section class="cli">

## CLI

<section class="usage">

### Usage

```text
Usage: read-file [options] <filepath>

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
  --enc, --encoding encoding   Encoding.
         --flag flag           Flag. Default: 'r'.
```

</section>

<!-- /.usage -->

<section class="notes">

### Notes

-   Relative file paths are resolved relative to the current working directory.
-   Errors are written to `stderr`.
-   File contents are written to `stdout`.

</section>

<!-- /.notes -->

<section class="examples">

### Examples

```bash
$ read-file ./README.md
<file_contents>
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

<section class="links">

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

</section>

<!-- /.links -->