I have been using a similar technique with great effect: <input type="text" name="jscheck" value="fail" style="display:none" /> <script> $('input[name="js

I have been using a similar technique with great effect: <input type="text" name="jscheck" value="fail" style="display:none" /> <script> $('input[name="jscheck"]').val('pass'); </script> On the server side you need only check if the jscheck=pass. This comes with two caveats. If the spam bot supports JS, their submission will pass. If a user browser has JS disabled, their submission will fail. In production, this has worked really well for me.