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WordPress

WP_Theme_JSON::append_to_selector( string $selector, string $to_append ): string

Since
5.8.0, 6.1.0, 6.3.0
Source
wp-includes/class-wp-theme-json.php:1093
Appends a sub-selector to an existing one.

Description

Given the compounded $selector "h1, h2, h3" and the $to_append selector ".some-class" the result will be "h1.some-class, h2.some-class, h3.some-class".

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

$selectorstring
Original selector.
$to_appendstring
Selector to append.

Return value

string
The new selector.

Performance profile

How much work a call to WP_Theme_JSON::append_to_selector() 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
Light

Touches nothing outside its own arguments.

Scaling
Scales with input

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

Instructions
6–15

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 21.

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 one call costs · 2 distinct outcomes

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

WhenInstructionsCalls it makes
!$selector6none
$selector14–15explode()

Across PHP versions

PHPCompiledExecutedBranchesNotes
8.6-dev216–153
8.5216–153
8.4216–1536 fewer instructions than PHP 8.3
8.3279–213
8.2279–213
8.1279–213
7.4279–213

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 · 1

  • str_contains()Polyfill for `str_contains()` function added in PHP 8.0.

Source code

View on Trac View on GitHub 

	protected static function append_to_selector( $selector, $to_append ) {		if ( ! str_contains( $selector, ',' ) ) {			return $selector . $to_append;		}		$new_selectors = array();		$selectors     = explode( ',', $selector );		foreach ( $selectors as $sel ) {			$new_selectors[] = $sel . $to_append;		}		return implode( ',', $new_selectors );	}

Changelog

Introduced in 5.8.0. 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.

6.3.0
Removed append position parameter.from the docblock
6.1.0
Added append position.from the docblock
5.8.0
Introduced.from the docblock

About this page

Parsed data
Generated from the wordpress-develop 6.9.7 tag, from src/wp-includes/class-wp-theme-json.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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