onkeyup jQuery validation for Single Field

You may have requirement that's you need validate only particular field on onkeyup event, and other in normal way.

So you just need to select that particular field and apply keyup event to that field. When user type something on that field it will trigger keyup event where we check that particular field is valid.

here is the jQuery validatation script.

$(document).on('keyup blur click', '#email',function(){
      $(this).valid();
});

YOu may refer following tutorial..

CakePHP Auth Component Login Tutorial