title: execute controller/action from javascript in rails3
body: <p>I have a following function in my _new.html.erb. I would like to call a controller when the element_id_placeholder is changed: </p>
  
  <pre><code> &lt;script type="text/javascript"&gt;
  
      // When DOM loads, init the page.
      $(function() {
        // Executes a callback detecting changes with a frequency of 1 second
        $("#id_element_placeholder").observe_field(1, function( ) {                                       
          alert('Change observed! new value: ' + this.value );
          // call controller 
  
        });
      });
  
    &lt;/script&gt;
  </code></pre>
  
  <p>I'm using rails 3</p>