Barecode issue in sales and purchase order

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){
                is_empty = 1;
        if (is_empty ==0){