datalist = {{1, 2}, {2, 4}, {3, 8}, {4, 16}};
Button["Save", Export[SystemDialogInput["FileSave"], datalist, "Table"]]
After I run it, I can see the filename but cannot find it as a file. Thanks.
It works. Thank you.
It seems that without Method->"Queued" Export will not wait for your choice. Use it then:
Method->"Queued"
Export
Button["Save", Export[SystemDialogInput["FileSave"], datalist, "Table"], Method -> "Queued"]
