Selection count in extjs works too slow

Question

I use standart Ext.grid.Panel in extJs. I need to select up to 500 rows in grid, and I want to know how many rows I have selected. I do it in such way:

    multiSelect: true,
    listeners:
    {
        'select':
        function( combo, record)
        {
            mainNS.app.pagingTB.items.get('selected-sited').update(' count of selected rows: ' + 
            mainNS.app.mainGrid.getSelectionModel().getCount())
        }
    },

But it works too slow, how can I optimize this operation?

Answer 1

The select event will fire for every record during a multiple selection. So if n rows are being selected at once, that means you're updating the content and, most importantly, triggering a layout n times.

You have 2 options:

1. Listen to the selectionchange event, which will fire only once for a batch of selections.
2. Add buffer: 1 as an option to the select event, so it will buffer the event from firing until the last selection has occurred.

No. 1 is the preferred solution.