@stdlib/fs/resolve-parent-paths/README.md

Filesystem APIs.

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# resolveParentPaths

> Resolve paths from a set of paths by walking parent directories.

<section class="usage">

## Usage

```javascript
var resolveParentPaths = require( '@stdlib/fs/resolve-parent-paths' );
```

<a name="resolve-parent-paths"></a>

#### resolveParentPaths( paths\[, options], clbk )

Asynchronously resolves paths from a set of paths by walking parent directories.

```javascript
resolveParentPaths( [ 'package.json', 'package-lock.json' ], onPaths );

function onPaths( error, paths ) {
    if ( error ) {
        throw error;
    }
    console.log( paths );
    // => [...]
}
```

The function accepts the following `options`:

-   **dir**: base directory from which to begin walking. May be either an absolute path or a path relative to the current working directory.

-   **mode**: mode of operation. The following modes are supported:

    -   `first`: return the first resolved path.
    -   `some`: return one or more paths resolved within the first directory level containing a match.
    -   `all`: return all resolved paths within the first directory level containing matches for all provided paths.
    -   `each`: independently return the first resolved path for each path at any directory level.
    
    Default: `'all'`.

By default, the function begins walking from the current working directory. To specify an alternative directory, set the `dir` option.

```javascript
var opts = {
    'dir': __dirname
};
resolveParentPaths( [ 'package.json' ], opts, onPaths );

function onPaths( error, paths ) {
    if ( error ) {
        throw error;
    }
    console.log( paths );
    // => [...]
}
```

By default, the function requires that a directory contains matches for all provided paths before returning results. To specify an alternative operation mode, set the `mode` option.

```javascript
var opts = {
    'dir': __dirname,
    'mode': 'first'
};
resolveParentPaths( [ 'package.json', 'package-lock.json' ], opts, onPaths );

function onPaths( error, paths ) {
    if ( error ) {
        throw error;
    }
    console.log( paths );
    // => [...]
}
```

#### resolveParentPaths.sync( paths\[, options] )

Synchronously resolves paths from a set of paths by walking parent directories.

```javascript
var paths = resolveParentPaths.sync( [ 'package.json', 'README.md' ] );
// returns [...]
```

The function accepts the same `options` as [`resolveParentPaths()`](#resolve-parent-paths).

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   In `some` mode, the return order of asynchronously resolved paths is not guaranteed.
-   This implementation is **not** similar in functionality to core [`path.resolve`][node-core-path-resolve]. The latter performs string manipulation to generate a full path. This implementation walks parent directories to perform a **search**, thereby touching the file system. Accordingly, this implementation resolves _real_ absolute file paths and is intended for use when a target's location in a parent directory is unknown relative to a child directory; e.g., when wanting to find a package root from deep within a package directory. 

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var resolveParentPaths = require( '@stdlib/fs/resolve-parent-paths' );

var opts = {
    'dir': __dirname
};

/* Sync */

var out = resolveParentPaths.sync( [ 'package.json', 'README.md' ], opts );
// returns [...]

out = resolveParentPaths.sync( [ 'non_existent_basename' ], opts );
// returns []

opts.mode = 'first';
out = resolveParentPaths.sync( [ 'non_existent_basename', 'package.json' ], opts );
// returns [...]

/* Async */

resolveParentPaths( [ 'package.json', 'README.md' ], opts, onPaths );
resolveParentPaths( [ './../non_existent_path' ], onPaths );

function onPaths( error, paths ) {
    if ( error ) {
        throw error;
    }
    console.log( paths );
}
```

</section>

<!-- /.examples -->

* * *

<section class="cli">

## CLI

<section class="usage">

### Usage

```text
Usage: resolve-parent-paths [options] <path> [<path>...]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --dir dir             Base search directory.
         --mode mode           Mode of operation.
```

</section>

<!-- /.usage -->

<section class="examples">

### Examples

```bash
$ resolve-parent-paths package.json package-lock.json
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

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<section class="related">

</section>

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<section class="links">

[node-core-path-resolve]: https://nodejs.org/api/path.html#path_path_resolve_paths

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

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</section>

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