Wordpress functions for all blog pages (body classes and menu items)

Wordpress blog pages functions

/**
 * Define if the current page is a blog page or not
 *
 * @global $post
 * @return bool     true if current page is a blog page
 */
function is_blog () {
	global  $post;
	return ( ( is_archive() || is_author() || is_category() || is_home() || is_single() || is_tag() ) && get_post_type( $post ) == 'post' );
}


/**
 * Adds a class group-blog to all blog pages
 *
 * @param  array   $classes Classes for the body element.
 * @return array   $classes
 */
function my_body_classes( $classes ) {
	if ( is_blog() ) {
		$classes[] = 'group-blog';
	}
	return $classes;
}
add_filter( 'body_class', 'my_body_classes' );


/**
 * Highlight all blog pages in menus
 * 
 * @param  array    $classes    Classes for the menu item
 * @param  bool|obj $menu_item  The menu item
 * @return array    $classes
 */
function my_menu_item_custom_class( $classes=array(), $menu_item=false ) {
	$page_for_posts = get_option( 'page_for_posts' );
	if ( is_blog() && $menu_item->object_id == $page_for_posts && !in_array( 'current-menu-item', $classes ) ) {
		$classes[] = 'current-menu-item';
	}
	return $classes;
}
add_filter('nav_menu_css_class', 'my_menu_item_custom_class', 100, 2);