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WordPress

render_block_core_footnotes( array $attributes, string $content, WP_Block $block ): string

Since
6.3.0
Source
wp-includes/blocks/footnotes.php:19
Renders the core/footnotes block on the server.

Compatibility

WordPress
since 6.3.0
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$attributesarray
Block attributes.
$contentstring
Block default content.
$blockWP_Block
Block instance.

Return value

string
Returns the HTML representing the footnotes.

Performance profile

How much work a call to render_block_core_footnotes() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class
Heavy

Reaches the database via get_post().

Scaling
Scales with input

The body loops, so the work grows with what you pass in.

Instructions
7–47

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 81.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

  • serializeserialisationjson_decode()called directly
  • querycontent queryget_post()one call below render_block_core_footnotes()
  • hookthird-party callbacksapply_filters()one call below render_block_core_footnotes()

Further down the call graph this can also reach option, cache and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 5 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost render_block_core_footnotes() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
empty($value)7none
!empty($value) && post_password_required()14post_password_required()
!empty($value) && !post_password_required()24post_password_required(), get_post_meta()
!empty($value) && !post_password_required()31–34post_password_required(), get_post_meta(), json_decode()
!empty($value) && !post_password_required() && is_array($footnotes)46–47post_password_required(), get_post_meta(), json_decode(), get_block_wrapper_attributes(), sprintf()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 81 instructions, 7–47 executed per call, 7 branches. The work does not change between versions.

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Uses · 6

  • post_password_required()Determines whether the post requires password and whether a correct password has been provided.
  • get_post_meta()Retrieves a post meta field for the given post ID.
  • get_block_wrapper_attributes()Generates a string of attributes by applying to the current block being rendered all of the features that the block supports.
  • __()Retrieves the translation of $text.
  • esc_attr()Escaping for HTML attributes.
  • wp_kses_post()Sanitizes content for allowed HTML tags for post content.

Source code

View on Trac View on GitHub 

function render_block_core_footnotes( $attributes, $content, $block ) {	// Bail out early if the post ID is not set for some reason.	if ( empty( $block->context['postId'] ) ) {		return '';	} 	if ( post_password_required( $block->context['postId'] ) ) {		return '';	} 	$footnotes = get_post_meta( $block->context['postId'], 'footnotes', true ); 	if ( ! $footnotes ) {		return '';	} 	$footnotes = json_decode( $footnotes, true ); 	if ( ! is_array( $footnotes ) || count( $footnotes ) === 0 ) {		return '';	} 	$wrapper_attributes = get_block_wrapper_attributes();	$footnote_index     = 1; 	$block_content = ''; 	foreach ( $footnotes as $footnote ) {		// Translators: %d: Integer representing the number of return links on the page.		$aria_label     = sprintf( __( 'Jump to footnote reference %1$d' ), $footnote_index );		$block_content .= sprintf(			'<li id="%1$s">%2$s <a href="#%1$s-link" aria-label="%3$s">↩︎</a></li>',			esc_attr( $footnote['id'] ),			wp_kses_post( $footnote['content'] ),			esc_attr( $aria_label )		);		++$footnote_index;	} 	return sprintf(		'<ol %1$s>%2$s</ol>',		$wrapper_attributes,		$block_content	);}

Changelog

Introduced in 6.3.0. Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data
Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/blocks/footnotes.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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