Replace Loop with Pipeline

Goal

Filter / map / reduce expresses the transformation as a sequence of named operations; intent jumps off the page.

Before the refactoring

const seniors = [];
for (const u of users) {
  if (u.age >= 65) seniors.push(u.name);
}

After the refactoring

const seniors = users
  .filter(u => u.age >= 65)
  .map(u => u.name);

Savings

Off-by-one and accumulator bugs vanish; each step is independently testable.

Note

Pipelines add a tiny per-element function-call overhead — usually negligible, but profile if you're in a hot path.