updateItem

Method which updates the edited table row passed as an argument or the row corresponding to the index passed as an argument. The updated data will be taken from the edit form editors.

updateItem(gridItem) or updateItem(index)
gridItem	HTML row object - <tr>	The edited row that will be updated.
index	Integer	The edited row corresponding to the index will be updated.

Example:

function UpdateFirstItem() {
    var masterTable = $find("<%= RadGrid1.ClientID %>").get_masterTableView();
    masterTable.updateItem(masterTable.get_dataItems()[0].get_element());
}