@stdlib/regexp/duration-string/README.md

Regular expressions.

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# reDurationString

> [Regular expression][mdn-regexp] to match a duration string.

<section class="usage">

## Usage

```javascript
var reDurationString = require( '@stdlib/regexp/duration-string' );
```

#### reDurationString()

Returns a [regular expression][mdn-regexp] to match a duration string.

```javascript
var RE_DURATION = reDurationString();
// returns <RegExp>

var parts = RE_DURATION.exec( '3d2ms' );
/* returns
    [
        '3d2ms',
        '3d',
        undefined,
        undefined,
        undefined,
        '2ms',
        index: 0,
        input: '3d2ms',
        groups: undefined
    ]
*/

parts = RE_DURATION.exec( '4h3m20s' );
/* returns
    [
        '4h3m20s',
        undefined,
        '4h',
        '3m',
        '20s',
        undefined,
        index: 0,
        input: '4h3m20s',
        groups: undefined
    ]
*/
```

#### reDurationString.REGEXP

[Regular expression][mdn-regexp] to match a duration string.

```javascript
var bool = reDurationString.REGEXP.test( '3d12h' );
// returns true
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   A duration string is a string containing a sequence of time units. A time unit is a nonnegative integer followed by a unit identifier. The following unit identifiers are supported:

    -   `d`: days
    -   `h`: hours
    -   `m`: minutes
    -   `s`: seconds
    -   `ms`: milliseconds

    For example, the string `1m3s10ms` is a duration string containing three time units: `1m` (1 minute), `3s` (3 seconds), and `10ms` (10 milliseconds). The string `60m` is a duration string containing a single time unit: `60m` (60 minutes). Time units must be supplied in descending order of magnitude (i.e., days, hours, minutes, seconds, milliseconds).

-   Duration strings are case insensitive. For example, the string `1M3S10MS` is equivalent to `1m3s10ms`.

-   The regular expression captures the following groups:

    1.  The days component.
    2.  The hours component.
    3.  The minutes component.
    4.  The seconds component.
    5.  The milliseconds component.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var reDurationString = require( '@stdlib/regexp/duration-string' );

var RE_DURATION = reDurationString();

var bool = RE_DURATION.test( '3d12h' );
// returns true

bool = RE_DURATION.test( '1M3S10MS' );
// returns true

bool = RE_DURATION.test( '1y.0w.0d' );
// returns false

bool = RE_DURATION.test( '1y3w' );
// returns false

bool = RE_DURATION.test( 'beep' );
// returns false
```

</section>

<!-- /.examples -->

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

<section class="related">

</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">

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

</section>

<!-- /.links -->