I want to add delivery date to the sales order form automatically and this should not change the values in the past forms

frappe.ui.form.on(“Sales Order”,{
setup(frm){
var date=frm.doc.transaction_date;
frm.set_value(“delivery_date”, frappe.datetime.add_days(frm.doc.transaction_date,35));
frm.refresh_field(“delivery_date”);}

});

frappe.ui.form.on(‘Sales Order’, {
setup: function (frm){
var date=frm.doc.transaction_date;
frm.set_value(‘delivery_date’, frappe.datetime.add_days(frm.doc.transaction_date,35));
frm.refresh_field(‘delivery_date’);
},
})

@parthvash1 try this it works in my local.

frappe.ui.form.on(“Sales Order”,{

  onload(frm){
  if(frm.doc.__islocal==1){
  frm.set_value("delivery_date", frappe.datetime.add_days(frm.doc.transaction_date,35));
  frm.refresh_field("delivery_date");
       if(frappe.datetime.get_day_diff(transaction_date, delivery_date) > 35){
            validate=false;
            frm.refresh_field("delivery date");
            frappe.msgprint("delivery Date cannot be a more than 35 days"); 
}

thanks ,I eventually wrote this code it works