Addition of two coloumn values

ok…

hey it’s working…thank you so much…
but When we add new row,previous row- amount coloumn it takes only product rate value(firstly shows addition value,after inserting next row amount value changes it shows only product rate value)

can you upload any screenshot?

ok. I ll upload

try:

frappe.ui.form.on("Sales Invoice Item", {
	validate: function(frm, cdt, cdn) {
		var d = locals[cdt][cdn];
		var total = 0;
		frappe.model.set_value(d.doctype, d.name, "amount", d.labour_rate + d.rate);
        refresh_field("amount","rate");
        
	}
});