wp-includes/kses.php:1224Removes all attributes, if none are allowed for this element.
$elementstring$attrstring$allowed_htmlarray[]|string$allowed_protocolsstring[]stringfunction 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 ); // Check if there are attributes that are required. $required_attrs = array_filter( $allowed_html[ $element_low ], static function ( $required_attr_limits ) { return isset( $required_attr_limits['required'] ) && true === $required_attr_limits['required']; } ); /* * If a required attribute check fails, we can return nothing for a self-closing tag, * but for a non-self-closing tag the best option is to return the element with attributes, * as KSES doesn't handle matching the relevant closing tag. */ $stripped_tag = ''; if ( empty( $xhtml_slash ) ) { $stripped_tag = "<$element>"; } // Go through $attrarr, and save the allowed attributes for this element in $attr2. $attr2 = ''; foreach ( $attrarr as $arreach ) { // Check if this attribute is required. $required = isset( $required_attrs[ strtolower( $arreach['name'] ) ] ); if ( wp_kses_attr_check( $arreach['name'], $arreach['value'], $arreach['whole'], $arreach['vless'], $element, $allowed_html ) ) { $attr2 .= ' ' . $arreach['whole']; // If this was a required attribute, we can mark it as found. if ( $required ) { unset( $required_attrs[ strtolower( $arreach['name'] ) ] ); } } elseif ( $required ) { // This attribute was required, but didn't pass the check. The entire tag is not allowed. return $stripped_tag; } } // If some required attributes weren't set, the entire tag is not allowed. if ( ! empty( $required_attrs ) ) { return $stripped_tag; } // Remove any "<" or ">" characters. $attr2 = preg_replace( '/[<>]/', '', $attr2 ); return "<$element$attr2$xhtml_slash>";}Introduced in 1.0.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/kses.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.