CashRegister example with docket

gistfile1.txt

        function calculateChange() {
            var purchase = document.getElementById('purchase');
            var cash = document.getElementById('cash');
            var change = document.getElementById('change');

            var result = Number(cash.value) - Number(purchase.value);
            console.log(result);

            change.value = result;

            // Update docket
            var dPurchase = document.getElementById('dPurchase');
            var dCash = document.getElementById('dCash');
            var dChange = document.getElementById('dChange');
            var dVat = document.getElementById('dVat');
            dPurchase.innerHTML = purchase.value;
            dCash.innerHTML = cash.value;
            dChange.innerHTML = change.value;
            dVat.innerHTML = (purchase.value * 7 / 107).toPrecision(2);
        }