@stdlib/string/reverse/README.md

String manipulation functions.

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# reverseString

> Reverse a string.

<section class="usage">

## Usage

```javascript
var reverseString = require( '@stdlib/string/reverse' );
```

#### reverseString( str\[, options] )

Reverses a `string`.

```javascript
var out = reverseString( 'last man standing' );
// returns 'gnidnats nam tsal'

out = reverseString( 'Hidden Treasures' );
// returns 'serusaerT neddiH'

out = reverseString( 'Lorem ipsum 𝌆 dolor sit ameͨ͆t.' );
// returns '.teͨ͆ma tis rolod 𝌆 muspi meroL'
```

The function supports the following options:

-   **mode**: type of characters to reverse. Must be one of the following:

    -   `'grapheme'`: grapheme clusters. Appropriate for strings containing visual characters which can span multiple Unicode code points (e.g., emoji).
    -   `'code_point'`: Unicode code points. Appropriate for strings containing visual characters which are comprised of more than one Unicode code unit (e.g., ideographic symbols and punctuation and mathematical alphanumerics).
    -   `'code_unit'`: UTF-16 code units. Appropriate for strings containing visual characters drawn from the basic multilingual plane (BMP) (e.g., common characters, such as those from the Latin, Greek, and Cyrillic alphabets).

    Default: `'grapheme'`.

</section>

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<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   By default, the function assumes the general case in which an input string may contain an arbitrary number of grapheme clusters. This assumption comes with a performance cost. Accordingly, if an input string is known to only contain visual characters of a particular type (e.g., only alphanumeric), one can achieve better performance by specifying the appropriate `mode` option.

</section>

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<section class="examples">

## Examples

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

```javascript
var reverseString = require( '@stdlib/string/reverse' );

var str = reverseString( 'last man standing' );
// returns 'gnidnats nam tsal'

str = reverseString( 'presidential election' );
// returns 'noitcele laitnediserp'

str = reverseString( 'javaScript' );
// returns 'tpircSavaj'

str = reverseString( 'Hidden Treasures' );
// returns 'serusaerT neddiH'
```

</section>

<!-- /.examples -->

* * *

<section class="cli">

## CLI

<section class="usage">

### Usage

```text
Usage: reverse [options] [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
         --mode mode           Type of character to return. Default: 'grapheme'.
```

</section>

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<!-- CLI usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

### Notes

-   If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.

    ```bash
    # Not escaped...
    $ echo -n $'beep\nboop' | reverse --split /\r?\n/

    # Escaped...
    $ echo -n $'beep\nboop' | reverse --split /\\r?\\n/
    ```

-   The implementation ignores trailing delimiters.

</section>

<!-- /.notes -->

<section class="examples">

### Examples

```bash
$ reverse foobar
raboof
```

To use as a [standard stream][standard-streams],

```bash
$ echo -n 'foobar' | reverse
raboof
```

By default, when used as a [standard stream][standard-streams], the implementation assumes newline-delimited data. To specify an alternative delimiter, set the `split` option.

```bash
$ echo -n 'foobar\tbaz' | reverse --split '\t'
raboof
zab
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

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

<section class="related">

</section>

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<section class="links">

[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams

</section>

<!-- /.links -->