REST APIs & Middleware

Which HTTP method is idempotent — calling it multiple times gives the same result?

What is CORS and why is it needed?

What does this middleware do?

app.use((req, res, next) => {
  const start = Date.now()
  next()
  const duration = Date.now() - start
  console.log(`${req.method} ${req.url} - ${duration}ms`)
})