wp-anti-comment-spam.php

<?php
	///////////////////////////////////
	# Enqueue Human Comment Script
	///////////////////////////////////
	add_action('wp_enqueue_scripts', 'add_human_comment_script'); // Add Theme Stylesheet
	function add_human_comment_script(){
		wp_register_script('human_comments', admin_url() . 'admin-ajax.php?action=human_comments_script', array('jquery'), '1.0', true);
		wp_enqueue_script('human_comments');
	}
	
	///////////////////////////////
	# Human Comment Script
	///////////////////////////////
	add_action('wp_ajax_nopriv_'.'human_comments_script', 'human_comments_script');
	add_action('wp_ajax_'.'human_comments_script', 'human_comments_script');
	function human_comments_script(){
		
		# Begin Output button
		ob_start();
		
		# Display the output
		?>
		<script>
			jQuery(document).ready(function($){
				$(window).on('load reloaded', function(){
					$('#respond form').not('.human-binded').each(function(){
						var $form = $(this).addClass('human-binded');
						$form.append('<input type="hidden" name="my_secret" value="1" />');
					});
				});
			});
		</script>
		<?php
		
		# Capture the output
		$output = ob_get_contents();
		ob_end_clean();
		
		# Remove script tags
		$output = str_replace('<script>', '', $output);
		$output = str_replace('</script>', '', $output);
		
		# Output the results
		header('Content-Type: text/javascript');
		echo $output;
		
		exit();
		
	}
	
	///////////////////////////////
	# Filter Comment Submit
	///////////////////////////////
	add_action('wp_insert_comment', 'remove_non_human_comments', 10, 2);
	function remove_non_human_comments( $id, $comment){
		if(empty($_POST['my_secret'])){
			wp_delete_comment($id, $force_delete = true);	// Delete the inserted comment
			$error = __('<strong>Something wrong happened to your comment submission!</strong> <br />Please make sure you have JavaScript enabled and try again.', TEXTDOMAIN);
			wp_die( $error );
		}
	}
?>