title: jQuery autocomplete - data.split is not a function
body: <p>I am using jQuery plugin autocomplete in web application and i pass simple json data to the autocomplete.
  When i pass data this way, by the variable words. Autocomlete works fine.</p>
  
  <pre>
  var words = ["benzina","best","benátská noc","bez realitky","beroun","bershka","bernard","beskydy","belgie","berlin"];
  $(document).ready(function() {
    $("#suggest").autocomplete(words, {
      formatItem: function(data, i, n) {
        return data[0];
      },  
        width: 342
    });
  });
  </pre>
  
  <p>But when I download it from server I get this error message "data.split is not a function". 
  I also set header Content-type: application/json in my server side script. I also try set option in autocommplete dataType: 'json', but still the same problem. 
  When i parse data in autocomplete option parse: function(data) { .. } it looks, that data are OK, but i cannot read it in formatItem. Do you have got any idea?</p>
  
  <pre>
  $(document).ready(function() {
    $("#suggest").autocomplete("ajax.php?gsug="+whisp_id, {
      formatItem: function(data, i, n) {
        return data[0];
      },  
        width: 342
    });
  });
  </pre>