Function Factory After

function-factory-after.js

//function injection again
function getTotal(lineItems, taxFunc) {
  let subtotal = lineItems.reduce((total, lineItem) => {
    return total += lineItem.total
  });
  return subtotal + taxFunc(subtotal));
}

//function factory
function salesTaxFunc(state) {
  switch(state) {
    case 'ak': return subTotal => { subTotal };
    case 'co': return subTotal => { subTotal * .029 };
    case 'ca': return subTotal => { subTotal * .075 };
  }
}

let taxFunc = salesTaxFunc('ca');
getTotal(lineItems, taxFunc);