Twenty Nineteen: Add fragment ID to paginated links

[laurelfulford]

Originally reported by @joyously in the Twenty Nineteen GitHub repo:

When the post/page has a featured image and is paginated, it shows the big image on each page. That is fine, but we could use code such as this so that the page links go to #content.

/**
 * Add a fragment identifier (to the content) to paginated links.
 */
function twentynineteen_link_pages_link( $link, $i ) {
	if ( $i > 1 && preg_match( '/href="([^"]*)"/', $link, $matches ) ) {
		if ( false === strpos( $matches[1], '#' ) ) {
			$link = str_replace( $matches[1], $matches[1] . '#content', $link );
		}
	}
	return $link;
}
add_filter( 'wp_link_pages_link', 'twentynineteen_link_pages_link', 10, 2 );

Original ticket: ​https://github.com/WordPress/twentynineteen/issues/381

[mukesh27]

@laurelfulford and @joyously above code is not working for Plain permalink structure. please try below code also attached patch for same in theme.

/**
 * Add a fragment identifier (to the content) to paginated links.
 */
function twentynineteen_link_pages_link( $link, $i ) {
	if ( $i > 1 && preg_match( '/href="([^"]*)"/', $link, $matches ) ) {
		$link = str_replace( $matches[1], $matches[1] . '#content', $link );
	}
	return $link;
}
add_filter( 'wp_link_pages_link', 'twentynineteen_link_pages_link', 10, 2 );

[mukesh27]

Patch tested for Plain, Day and name, Month and name, Numeric, Post name and Custom Structure permalink structures.

[joyously]

I am getting the same result (not working on Plain permalinks), but I don't see why.

Do you know why?

The case that check is for is if there is already some other filter(like a plugin) for the link adding a fragment ID. It shouldn't make it into an invalid link.