Substitute Algorithm

Goal

An opaque or convoluted algorithm gets replaced by a clearer one (often from a library or well-known pattern) that produces the same outputs.

Before the refactoring

function found(people, n) {
  for (const p of people) if (p.name === n) return p;
  return null;
}

After the refactoring

function found(people, n) {
  return people.find(p => p.name === n) ?? null;
}

Savings

Future maintainers read the well-known pattern instead of decoding the bespoke implementation; performance and correctness usually improve.

Note

Swapping algorithms wholesale forfeits behavioral safety — characterize the function with tests at every input boundary you care about before substituting.