private function iterateFiles(dir:File):void
{
    if (!dir.isDirectory || dir.isHidden || !dir.exists || dir.name.search(/^\..*$/) != -1) return;
    var listing:Array = dir.getDirectoryListing();
    for each(var f:File in listing)
    {
        if (this.fileList.length >= this.MAX_FILES) break;
        if (f.isHidden || !f.exists || f.name.search(/^\..*$/) != -1) continue;
        if (f.isDirectory)
        {
            this.iterateFiles(f);
        }
        else
        {
            this.fileList.push(f);
        }
    }
}

http://blogs.adobe.com/cantrell/archives/2009/07/ignoring-hidden.html

Ignoring Hidden Files in AIR

file

ActionScript 3