function apply_filters($tag, $value) {}

Call the functions added to a filter hook.
The callback functions attached to filter hook $tag are invoked by calling this function. This function can be used to create a new filter hook by simply calling this function with the name of the new hook specified using the $tag parameter.


  • string $tag: The name of the filter hook.
  • mixed $value: The value on which the filters hooked to <tt>$tag</tt> are applied on.
  • mixed $var,…: Additional variables passed to the functions hooked to <tt>$tag</tt>.

Return values

returns:The filtered value after all hooked functions are applied to it.

Defined filters

  • $tag
    apply_filters($tag, $value)

Source code

function apply_filters($tag, $value) {

	global $wp_filter, $merged_filters, $wp_current_filter;

	$args = array();

	// Do 'all' actions first

	if ( isset($wp_filter['all']) ) {

		$wp_current_filter[] = $tag;

		$args = func_get_args();



	if ( !isset($wp_filter[$tag]) ) {

		if ( isset($wp_filter['all']) )


		return $value;


	if ( !isset($wp_filter['all']) )

		$wp_current_filter[] = $tag;

	// Sort

	if ( !isset( $merged_filters[ $tag ] ) ) {


		$merged_filters[ $tag ] = true;


	reset( $wp_filter[ $tag ] );

	if ( empty($args) )

		$args = func_get_args();

	do {

		foreach( (array) current($wp_filter[$tag]) as $the_ )

			if ( !is_null($the_['function']) ){

				$args[1] = $value;

				$value = call_user_func_array($the_['function'], array_slice($args, 1, (int) $the_['accepted_args']));


	} while ( next($wp_filter[$tag]) !== false );

	array_pop( $wp_current_filter );

	return $value;



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