Function Factory Before

function-factory.js

function getTotal(lineItems, state) {
  let subtotal = lineItems.reduce((total, lineItem) => {
    return total += lineItem.total
  });
  return subtotal + salesTax(state, subtotal));
}

function salesTax(state, subtotal) {
  switch(state) {
    case 'ak': return 0;
    case 'co': return .029 * subtotal;
    case 'ca': return .075 * subtotal;
  }
}

getTotal(lineItems, 'ca');