Hi,
This property is not available by default in DFFS, but you can use a query like this in the custom js:
var checkedOut = false;
var checkedOutRes = spjs.utility.getItemByID({"listName":_spPageContextInfo.pageListId,"id":spjs.dffs.data.thisItemID,"viewFields":["CheckoutUser"]});
if(checkedOutRes.CheckoutUser !== null){
checkedOut = true;
}
// Use the checkedOut variable to do something here
Hope you can use this snippet.
Alexander