Automatic Delivery Date on Sales Order

Frappe Framework Customization
1

Hi… I’m new here

How I can auto fill delivery date +2 days from sales order date.
Thanks

2 
frappe.ui.form.on("Put Doctype Name Here",
{
          sales_order_date: function(frm)
          {
		            assign_date(frm);
	      }
});

var assign_date = function(frm)
{
      frm.set_value("delivery_date", frappe.datetime.add_days(doc.sales_order_date, 2));
}