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.

[poena]

I have tested the patch on WordPress 6.2, theme version 2.5.
I did two tests, one with the page break block and one with a classic block and manually adding

<p><!--nextpage--></p>

Targetting the #content works well for all permalinks.

[alvitazwar052]

Test Report

Environment

• OS: macOS 12.4
• Web Server: Nginx
• PHP: 7.4.33
• WordPress: 6.3-alpha-55505-src
• Browser: Chrome
• Theme: Twenty-nineteen

Screenshots

Pagination:

1. ​https://prnt.sc/NjIM9JiNo3bi
2. ​https://prnt.sc/RV--wuCvTNBL

Results

• I've tested with block editor with Plain, Day and name, Month and name, Numeric, Post name, and Custom Structure permalink structures. Targeting the #content works well for all permalinks. Pagination is also working as expected

[oglekler]

I wonder if this needs Unit-tests as well. @mukesh27 what do you think?

[audrasjb]

I don't think we need unit tests here, as this function would only be used by this specific theme :)

Trac ticket: https://core.trac.wordpress.org/ticket/45920

Trac ticket: https://core.trac.wordpress.org/ticket/45920

[mukesh27]

@audrasjb i open PR added missing document for the function. Feel free to take a look.

[oglekler]

Patch is ready for testing

[audrasjb]

In 56057:

Twenty Nineteen: Add fragment ID to paginated links.

This changeset adds the #content fragment identifier to paginated links so the screen scrolls down to the content section when clicking on pagination links
located on paginated pages.

Props laurelfulford, mukesh27, joyously, poena, alvitazwar052, oglekler, audrasjb.
Fixes #45920.

committed in https://core.trac.wordpress.org/changeset/56057