I want to select all rows of a grid by default, and I managed to do so by adding a data listener in onRegisterApi as specified in this answer:
onRegisterApi : function(gridApi)
    {
      $scope.gridApi = gridApi; 
      $scope.gridApi.grid.registerDataChangeCallback(function(data)
        {
          $scope.gridApi.selection.selectRow($scope.gridOptions.data[0]);
        }, [uiGridConstants.dataChange.ROW]);
    }
Working plunkr: http://plnkr.co/edit/dzf6PZwKdZmSNvKzQeYH?p=preview
However, I don't understand why it doesn't work without a listener, like
onRegisterApi : function(gridApi)
    {
      $scope.gridApi = gridApi; 
        _.each($scope.gridOptions.data, function(companies, index){
          $scope.gridApi.selection.selectRow($scope.gridOptions.data[index]);
      });
    }
Non-working plunkr: http://plnkr.co/edit/XOliwXn2MLyH6nqO7pp4?p=preview
Can someone tell me why?
 
     
     
    