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WordPress

wp_check_jsonp_callback( string $callback ): bool

Since
4.6.0
Source
wp-includes/functions.php:4699
Checks that a JSONP callback is a valid JavaScript callback name.

Description

Only allows alphanumeric characters and the dot character in callback function names. This helps to mitigate XSS attacks caused by directly outputting user input.

Compatibility

WordPress
since 4.6.0
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

$callbackstring
Supplied JSONP callback function name.

Return value

bool
Whether the callback function name is valid.

Performance profile

How much work a call to wp_check_jsonp_callback() 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
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
4–12

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 13.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
2

2 places in core call this, so the cost is paid more often than your own code shows.

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_check_jsonp_callback() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
!is_string($callback)4none
is_string($callback)12preg_replace()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 13 instructions, 4–12 executed per call, 1 branch. 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.

Used by · 2

Source code

View on Trac View on GitHub 

function wp_check_jsonp_callback( $callback ) {	if ( ! is_string( $callback ) ) {		return false;	} 	preg_replace( '/[^\w\.]/', '', $callback, -1, $illegal_char_count ); 	return 0 === $illegal_char_count;}

Changelog

Introduced in 4.6.0. 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/functions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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