look at the link description when looking at the paging
the blogger says that what is provided at the bottom of the laravel needs to use. I directly use UrlWindow; what"s wrong?
$window = UrlWindow::make ($posts);

public function fetch()
{
    // 62
    $posts = Post::paginate(6)->onEachSide(2)->withPath(url("post"));
    // URL
    $window = UrlWindow::make($posts);
    $pages = array_filter([
        $window["first"],
        is_array($window["slider"]) ? "..." : null,
        $window["slider"],
        is_array($window["last"]) ? "..." : null,
        $window["last"],
    ]);
    return response()->json([
        "paginator" => $posts,
        "elements" => $pages
    ]);
}