@stdlib/assert/is-regexp-string/README.md

Standard assertion utilities.

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# isRegExpString

> Test if a value is a regular expression string.

<section class="intro">

</section>

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<section class="usage">

## Usage

```javascript
var isRegExpString = require( '@stdlib/assert/is-regexp-string' );
```

#### isRegExpString( value )

Tests if a `value` is a regular expression `string`.

```javascript
var bool = isRegExpString( '/^beep$/' );
// returns true
```

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<section class="examples">

## Examples

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

```javascript
var isRegExpString = require( '@stdlib/assert/is-regexp-string' );

var bool;

bool = isRegExpString( '/beep/' );
// returns true

bool = isRegExpString( '/beep/gim' );
// returns true

bool = isRegExpString( 'beep' );
// returns false

bool = isRegExpString( '' );
// returns false

bool = isRegExpString( null );
// returns false
```

</section>

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* * *

<section class="cli">

## CLI

<section class="usage">

### Usage

```text
Usage: is-regexp-string [options] [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
```

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<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 booP\n/beep/' | is-regexp-string --split /\r?\n/
    # Escaped...
    $ echo -n $'beEp booP\n/beep/' | is-regexp-string --split /\\r?\\n/
    ```

-   The implementation ignores trailing delimiters.

</section>

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<section class="examples">

### Examples

```bash
$ is-regexp-string '/beep/'
true
```

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

```bash
$ echo -n '/beep/' | is-regexp-string
true
```

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 'beep\t/boop/' | is-regexp-string --split '\t'
false
true
```

</section>

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</section>

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* * *

## See Also

-   <span class="package-name">[`@stdlib/assert/is-regexp`][@stdlib/assert/is-regexp]</span><span class="delimiter">: </span><span class="description">test if a value is a regular expression.</span>

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<section class="links">

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

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

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[@stdlib/assert/is-regexp]: https://github.com/stdlib-js/assert/tree/main/is-regexp

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</section>

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