Get the ID from posts, pages, and archives in WordPress

gistfile1.txt

if ( is_home() && ! in_the_loop() ) {
    $ID = get_option('page_for_posts');
} elseif ( is_post_type_archive()) {
    $query = get_queried_object();
    $slug = $query->name;
    $pageobj = get_page_by_title($slug);
    $ID = $pageobj->ID;
} else {
    $ID = get_the_ID();
}