Hi,

 

Developer can use client side Javascript and the FileValidating event at the sametime.

 

If server prepair enough meta data to client side , the invalid item can be cancelled by javascript easily.

 

And the FileValidating event is just for double check and prevent some hackers skip the javascript step.

 

That solution can implement most of the validation tasks.

 

 

Of cause you may need check the FileName or FileSize by ONLY-SERVER-LOGIC,

 

But we do not plan to add that server event ,

 

Just do not want to access the server too many times.

 

If more advanced developer ask that request, we'd like to provide samples instead buildin function.

 

 

Thank you.

 

Regards,
Terry