$isdir
From Scriptwiki
Returns informations on whether or not a directory exists.
$isdir(directory)
Returns $true if the directory exists, otherwise it will return $false
Examples
alias exists? { if ($isdir($1)) { return directory exists! } | else { return directory doesn't exist } }
$isdir(C:\program files\mirc)
See also
$isfile to check if a file exists.