It works in 1.8, the problem is 1.9: [[1]](http://stackoverflow.com/questions/15513263/jquery-1-9-1-property-selector), [[2]](http://jquery.com/upgrade-guide/1.9/#attr-versus-prop-), [[3]](http://stackoverflow.com/questions/5874652/prop-vs-attr)

This works:
```coffee
$.expr[':'].hasValue = (elem)->
  $elem = $(elem)
  $elem.is(':input') && $elem.val()

$ ->
  $('#q_search').submit ->
    $(@).find(':input:not(:hasValue)').prop 'disabled', true
```