get initial data from data table after filter

how to retrieve initially loaded data from data table after filter

if you mean unfiltered data then table.serialize(true);
https://docs.webix.com/api__link__ui.datatable_serialize.html

all:boolean argument is not documented though

you can use dt.filter() to reset a widget back to the initial state

also, there is a serialize API, if you need to get the data only
https://docs.webix.com/api__link__ui.proto_serialize.html