There is no sort event available in the dataSource. This suggestion is posted in our user voice portal
. If you consider that it will be useful addition to the framework, you could place your vote there. If it becomes popular among the community, we will consider to implement it in future releases.
As for the exact case, you could use the sort() method
of the dataSource to retrieve the current sort configuration and compare it will the previous one. For example a JS variable could be used to store the previous sort configuration.
I hope this information helps.
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