Can't upload js,css files in laravel with correct extension

I'm using jquery file-uploader to upload files with this

$('#fileupload').fileupload({
    formData: {_token: csrf_token },
    dataType: 'json',
    done: function (e, data) {
        addFileToTable(data);
    }
});

and try to save it in Laravel with a random name and the extension like this

if ($request->hasFile('files')) {
    $filepath = config('paths.files');
    $files = $request->file('files');
    $file = $files[0];
    $fileName = md5($file . microtime()) . '.' . $file->extension();
    $file->storeAs(
        $filepath, $fileName, 'public'
    );
    $isImage = substr($file->getMimeType(), 0, 5) == 'image';

    $fileObj = File::create([
        'name' => $fileName,
        'path' => '/storage/'.$filepath.$fileName,
        'isImage' => $isImage,
        'user_created' => auth()->id()
    ]);
    return response()->json(array('file' => $fileObj), 200);
}

but the problem is when i try to upload files like .css, .js, etc. Laravel sees the extension as .txt and saves it as .txt file

I don't know if the problem is in the Laravel or jquery-fileuploader

via Chebli Mohamed