重构手法探索器

function printOwing(invoice) {
  recordDueDate(invoice);
  printDetails(invoice, calculateOutstanding(invoice));
}

function calculateOutstanding(invoice) {
  let result = 0;
  for (const order of invoice.orders) {
    result += order.amount;
  }
  return result;
}

function recordDueDate(invoice) {
  const today = Clock.today;
  invoice.dueDate = new Date(today.getFullYear(), today.getMonth(), today.getDate() + 30);
}

function printDetails(invoice, outstanding) {
  printBanner();
  console.log(`name: ${invoice.customer}`);
  console.log(`amount: ${outstanding}`);
}

function printBanner() {
  console.log("***********************");
  console.log("**** Customer Owes ****");
  console.log("***********************");
}