"use strict"; const getElement = selector => document.querySelector(selector); document.addEventListener("DOMContentLoaded", () => { getElement("#calculate").addEventListener("click", () => { const taxRate = 0.0875; const subtotal = parseFloat(getElement("#subtotal").value); const invoice = new Invoice(subtotal, taxRate); getElement("#tax_amount").value = invoice.getSalesTax(); getElement("#total").value = invoice.getTotal(); }); });