code: function(path) {
      var state = window.history.state,
          initialURL = get(this, '_initialURL');
  
      path = this.formatPath(path);
  
      if ((initialURL !== path && !state) || (state && state.path !== path)) {
        window.history.pushState({ path: path }, null, path);
      }
    }
docs: @private
  
  Uses `history.pushState` to update the url without a page reload.