Long Method (ARCH3180)

Key typescript.quality.long-method · Severity info · Category quality

Functions whose body exceeds the line threshold do too much at once; they become hard to read, test, and change. Logical steps should be extracted into separate functions.

Incorrect

function processOrder(o: Order) {
  if (!o.items.length) throw new Error("empty");
  let total = 0;
  for (const i of o.items) total += i.price * i.qty;
  const tax = total * 0.18;
  const shipping = total > 500 ? 0 : 30;
  const discount = o.coupon ? total * 0.1 : 0;
  const grand = total + tax + shipping - discount;
  saveInvoice(o, grand);
  sendEmail(o.customer, grand);
  // ...dozens more lines
}

Correct

function processOrder(o: Order) {
  validate(o);
  const totals = computeTotals(o);
  saveInvoice(o, totals.grand);
  sendEmail(o.customer, totals.grand);
}

Fix

Split the method into small, single-responsibility helper functions.