Meteor-excel is not supported in Safari browser

[silverfangs]

I used the example codes from MeteorPad.

When I tried to download the excel file, the file format is not either in ".xlsx" or ".xls".
But when I add the ".xlsx" to the file, the data still retained.

But how do I fix it? So I don't need to add the ".xlsx" extension every time.
Thanks, guys.