I have to write this extra code in every doctype if want to user barcode to add items. New rows wont add without using this code in JS.
scan_barcode: function(frm){
var doc = cur_frm.doc;
var is_empty = 0;
for (var i in doc.items){
if(doc.items[i].item_code==undefined){
is_empty = 1;
}
}
if (is_empty ==0){
frm.add_child('items');
}
}