function isDurationString( value ) {
	if ( !isString( value ) ) {
		return false;
	}
	return RE_DURATION_STRING.test( value );
}
Tests if a value is a duration string.

## Notes

-   The function validates that a value is a string. For all other types, the function returns `false`.

-   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). A duration string must contain at least one time unit. 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`.

@param {*} value - value to test
@returns {boolean} boolean indicating if a value is a duration string

@example
var bool = isDurationString( '1d' );
// returns true

@example
var bool = isDurationString( '1d2h' );
// returns true