selectAllItems

Selects all items in the GridTableView for which the method is invoked.

The AllowMultiRowSelection property of RadGrid should be set to true to select multiple items!

selectAllItems()

Example:

function SelectMasterTableItems() {
    var masterTable = $find("<%= RadGrid1.ClientID %>").get_masterTableView();
    //select all master table items
    masterTable.selectAllItems();
}