<script type="text/javascript">
  jQuery(document).ready(function(){
    jQuery(#my_input).change(function(){
      var value = jQuery(#my_input).val();
      jQuery.ajax({
        url: {{ path('ParteAccidentes_ajax', {'emergencia': value}) }},
        timeout: 5000,
        success: function(data) {
          alert('ok');
        },
        error: function() {
          alert('mal');
        }
      });
    });
  });
</script>

<script type="text/javascript">
  jQuery(document).ready(function(){
    jQuery(#my_input).change(function(){
      var value = jQuery(#my_input).val();
      var url = "{{ path('ParteAccidentes_ajax', {'emergencia': 'text'}) }}";
      url = url.replace("text", value);
      jQuery.ajax({
        url: url,
        timeout: 5000,
        success: function(data) {
          alert('ok');
        },
        error: function() {
          alert('mal');
        }
      });
    });
  });
</script>