What is wrong with my js?

2

Hi @Omar_M_K_Shehada,

Code is right.

Please check it syntax.

frappe.ui.form.on('Your Child Table', {
	field_name_for_trigger: function(frm, cdt, cdn) {
		var row = local[cdt][cdn];
		// Your Code
	}
});

// Example:
frappe.ui.form.on('Sales Order Item', {
	qty: function(frm, cdt, cdn) {
		var row = local[cdt][cdn];
		frappe.model.set_value(cdt, cdn, 'custom_total_field', row.qty * row.rate);
	}
});

More reference for:

I hope this helps.

Thank You!