wp_kses_attr( string $element, string $attr, array $allowed_html, array $allowed_protocols )

Removes all attributes, if none are allowed for this element.


If some are allowed it calls wp_kses_hair() to split them further, and then it builds up new HTML code from the data that kses_hair() returns. It also removes "<" and ">" characters, if there are any left. One more thing it does is to check if the tag has a closing XHTML slash, and if it does, it puts one in the returned code as well.



(string) (Required) HTML element/tag


(string) (Required) HTML attributes from HTML element to closing HTML element tag


(array) (Required) Allowed HTML elements


(array) (Required) Allowed protocols to keep


(string) Sanitized HTML element


File: wp-includes/kses.php

function wp_kses_attr($element, $attr, $allowed_html, $allowed_protocols) {
	if ( ! is_array( $allowed_html ) )
		$allowed_html = wp_kses_allowed_html( $allowed_html );

	// Is there a closing XHTML slash at the end of the attributes?
	$xhtml_slash = '';
	if (preg_match('%\s*/\s*$%', $attr))
		$xhtml_slash = ' /';

	// Are any attributes allowed at all for this element?
	$element_low = strtolower( $element );
	if ( empty( $allowed_html[ $element_low ] ) || true === $allowed_html[ $element_low ] ) {
		return "<$element$xhtml_slash>";

	// Split it
	$attrarr = wp_kses_hair($attr, $allowed_protocols);

	// Go through $attrarr, and save the allowed attributes for this element
	// in $attr2
	$attr2 = '';
	foreach ( $attrarr as $arreach ) {
		if ( wp_kses_attr_check( $arreach['name'], $arreach['value'], $arreach['whole'], $arreach['vless'], $element, $allowed_html ) ) {
			$attr2 .= ' '.$arreach['whole'];

	// Remove any "<" or ">" characters
	$attr2 = preg_replace('/[<>]/', '', $attr2);

	return "<$element$attr2$xhtml_slash>";


Version Description
WP-1.0.0 Introduced.