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

Standard assertion utilities.

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# isHexString

> Test whether a string contains only hexadecimal digits.

<section class="usage">

## Usage

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

#### isHexString( value )

Tests whether a string contains only hexadecimal digits.

```javascript
var bool = isHexString( '0123456789abcdefABCDEF' );
// returns true
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   For non-string values, the function returns `false`.
-   The function does **not** recognize `x` (as in the standard `0x` prefix).

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

var out = isHexString( '0123456789abcdefABCDEF' );
// returns true

out = isHexString( '' );
// returns false

out = isHexString( '0xffffff' );
// returns false

out = isHexString( 123 );
// returns false
```

</section>

<!-- /.examples -->

* * *

<section class="cli">

## CLI

<section class="usage">

### Usage

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

Options:

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

</section>

<!-- /.usage -->

<!-- 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 $'0xffffff\n0123456789abcdefABCDEF' | is-hex-string --split /\r?\n/
    # Escaped...
    $ echo -n $'0xffffff\n0123456789abcdefABCDEF' | is-hex-string --split /\\r?\\n/
    ```

-   The implementation ignores trailing delimiters.

</section>

<!-- /.notes -->

<section class="examples">

### Examples

```bash
$ is-hex-string 0123456789abcdefABCDEF
true
```

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

```bash
$ echo -n '0123456789abcdefABCDEF' | is-hex-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 '0123456789abcdefABCDEF\t0xffffff' | is-hex-string --split '\t'
true
false
```

</section>

<!-- /.examples -->

</section>

<!-- /.cli -->

<!-- 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/assert/is-string`][@stdlib/assert/is-string]</span><span class="delimiter">: </span><span class="description">test if a value is a string.</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">

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

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

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

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

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

</section>

<!-- /.links -->