WordPress - Print out a list of all the hooked functions for a given tag (or all if no tag is passed). Builds a table showing rowed by priority.

hooked_functions.php

/**
 * An example of how to call it
 */
add_action( 'wp_head', function() { 
	print_list_hooked_functions( 'genesis_header' ); 
} );

/**
 * Print a list of all hooked functions
 *
 * @since  1.0.0
 * 
 * @param string 	$tag 	(optional) The name of the action to be evaluated.
 *                      	 Leave it blank to print all hooks.
 * @return void
 */
function print_list_hooked_functions( $tag = '' ) {
	global $wp_filter;

	if ( $tag ) {

		$hook[ $tag ] = isset( $wp_filter[ $tag ] ) ? $wp_filter[ $tag ] : null;

		//* If the $tag does not exist, then print a message and bail out.
		if ( empty( $hook[ $tag ] ) || ! is_array( $hook[ $tag ] ) ) {
			printf( '<p>%s %s.</p>', __( 'No hooks found for', 'lunarwp' ), $tag );
			return;
		}

	//* We'll do all of them
	} else {
		$hook = $wp_filter;
		ksort( $hook );
	}


	//* Loop through each of the hooks and print them out
	foreach ( $hook as $tag => $hooked_functions ) {
		
		//* print the first level
		printf( '<p style="margin-left: 40px;"><strong>%s</strong><br>', esc_html( $tag ) );

		echo '<table style="margin-left: 40px">';
		printf( '<thead><tr><th style="text-transform: capitalize;">%s</th><th style="text-transform: capitalize;">%s</th></tr></thead><tbody>', 
			__( 'Priority', 'lunarwp' ), 
			__( 'Hooked Function Name', 'lunarwp' )
		);

		ksort( $hooked_functions );

		//* Loop through the priorities and functions
		foreach ( $hooked_functions as $priority => $functions ) {

			//* Print the priority level
			printf( '<tr><td width="100px">%s</td><td>', esc_html( $priority ) );

			$function_names = array_keys( $functions );
			sort( $function_names );
			
			echo implode( '<br>', $function_names );

			echo '</td></tr>';
		}
		echo '</tbody></table></p>';
	}

}