code: function(i, j) {
          var info = null;
          if (this.json) {
              var id = this.getFeatureId(i, j);
              if (id !== null) {
                  info = {id: id, data: this.json.data[id]};
              }
          }
          return info;
      }
docs: Method: getFeatureInfo
  Get feature information associated with a pixel offset.  If the pixel
  offset corresponds to a feature, the returned object will have id
  and data properties.  Otherwise, null will be returned.
  
  
  Parameters:
  i - {Number} X-axis pixel offset (from top left of tile)
  j - {Number} Y-axis pixel offset (from top left of tile)
  
  Returns:
  {Object} Object with feature id and data properties corresponding to the
  given pixel offset.