wp_kses( string $string, array[]|string $allowed_html, string[] $allowed_protocols = array() )

Filters text content and strips out disallowed HTML.


Description

This function makes sure that only the allowed HTML element names, attribute names, attribute values, and HTML entities will occur in the given text string.

This function expects unslashed data.

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See also


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Parameters

$string

(string) (Required) Text content to filter.

$allowed_html

(array[]|string) (Required) An array of allowed HTML elements and attributes, or a context name such as 'post'. See wp_kses_allowed_html() for the list of accepted context names.

$allowed_protocols

(string[]) (Optional) Array of allowed URL protocols.

Default value: array()


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Return

(string) Filtered content containing only the allowed HTML.


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More Information

KSES is a recursive acronym which stands for “KSES Strips Evil Scripts”.

For parameter $allowed_protocols, the default allowed protocols are http, https, ftp, mailto, news, irc, gopher, nntp, feed, and telnet. This covers all common link protocols, except for javascript, which should not be allowed for untrusted users.


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Source

File: wp-includes/kses.php

function wp_kses( $string, $allowed_html, $allowed_protocols = array() ) {
	if ( empty( $allowed_protocols ) ) {
		$allowed_protocols = wp_allowed_protocols();
	}

	$string = wp_kses_no_null( $string, array( 'slash_zero' => 'keep' ) );
	$string = wp_kses_normalize_entities( $string );
	$string = wp_kses_hook( $string, $allowed_html, $allowed_protocols );

	return wp_kses_split( $string, $allowed_html, $allowed_protocols );
}


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Changelog

Changelog
Version Description
1.0.0 Introduced.

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User Contributed Notes

  1. Skip to note 1 content
    Contributed by Bart Kuijper

    Many function names in WordPress are self-explanatory and if they aren’t, their documentation usually sheds some light on how they got their name. I find this makes it easier to later recall their names and uses. However, wp_kses is an exception. So for anyone else wondering:

    kses comes from the terms XSS (cross-site scripting) and access. It’s also a recursive acronym (every open-source project should have one!) for “kses strips evil scripts”.

  2. Skip to note 2 content
    Contributed by Codex

    Allowed HTML tags array
    This is an example of how to format an array of allowed HTML tags and attributes.

    array(
        'a' => array(
            'href' => array(),
            'title' => array()
        ),
        'br' => array(),
        'em' => array(),
        'strong' => array(),
    );
    
    
  3. Skip to note 3 content
    Contributed by Abdul Hadi

    WordPress wp_kses is an HTML filtering mechanism. If you need to escape your output in a specific (custom) way, wp_kses function in WordPress will come handy.

    <?php
    $str = 'Check Kses function I am <strong>stronger</strong> and cooler every single day <a href="#" rel="nofollow ugc">Click Here</a>';
    echo $str;
    $arr = array( 'br' => array(), 'p' => array(), 'strong' => array() );
    echo 'String using wp_kses function....' . wp_kses( $str, $arr );
    ?>

    Output:
    Before wp_kses: Check Kses function I am stronger and cooler every single day Click Here
    After wp_kses: String using wp_kses function…. Check Kses function I am stronger and cooler every single day Click Here

    It will display a resultant string as shown in the output screen. It only reflects the allowed tags strong, br, p as defined in wp_kses function and anchor tag is removed. So, no link for click Here text is formed.

  4. Skip to note 5 content
    Contributed by TomS Caprice
    // Allowed img tag and support svg base64 data like:  <img src="data:image/svg+xml;base64,__base64_code__" />
    function wpdocs_allowed_html() {
    	return array(
    		'img' => array(
    			'title' => array(),
    			'src'	=> array(),
    			'alt'	=> array(),
    		)
    	);
    }
    
    function wpdocs_allowed_protocols() {
    	return array(
    		'data' 	=> array(),
    		'http'	=> array(),
    		'https' => array(),
    	);
    }
    
    function wpdocs_output_img() {
    	$html = '';
    	ob_start();
    	?>
    
    	<img src="data:image/svg+xml;base64,Your_base64_code" title="img_title" alt="alt_info" />
    
    	<?php 
    	$html = ob_get_contents();
    	ob_end_clean();
    	return $html;
    }
    
    $allowed_html      = wpdocs_allowed_html();
    $allowed_protocols = wpdocs_allowed_protocols();
    $wpdocs_img        = wpdocs_output_img();
    
    echo wp_kses( $wpdocs_img, $allowed_html, $allowed_protocols )

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