the plugin works by insisting that non-javascript-enabled clients enter a code provided by the blog in order to prove that there´s a human being running the client. the plugin assumes that if javascript is enabled, then it´s a real person using a real browser trying to add a comment, and not a web-bot running wordpress´s add-comment script directly.

the plugin can be found here:

http://wordpress.org/extend/plugins/jsspamblock/

when i activated the plugin, the database table was not automatically created. in case you need it, this is the SQL you need to create it manually:

CREATE TABLE `wp_jsspamblock` (
`ID` int(11) NOT NULL auto_increment,
`code` varchar(4) NOT NULL default ”,
`hash` varchar(32) NOT NULL default ”,
`expire` datetime NOT NULL default ’0000-00-00 00:00:00′,
PRIMARY KEY (`ID`),
UNIQUE KEY `hash` (`hash`),
KEY `code` (`code`)
) ENGINE=MyISAM ;

if the default table prefix in your wordpress setup is not ´wp_´, you´ll need to replace the ´wp_´ in the table name with whatever your default table prefix is.