Since the requestEnd is an event of the DataSource, it contains no information about the Grid that triggered the request. Furthermore, as the DataSource itself can be shared between multiple Grids, it does not have a property that points to the Grid that uses it.
As a work around, you can consider adding an event handler for the Grid operations that can fire DataSource events, e.g. sort
and store e.sender (the Grid instance) in a variable that you can use later in requestEnd. If you don't have other logic to execute, related to the given events, you can use a single event handler function for all events in all Grids:
currentGrid = e.sender;
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