Convert Callbacks and Promise Chains to async/await

Promise chains with nested .then() calls and old-style callbacks are perfectly valid JavaScript — but they're painful to read and extend. Claude can modernise them in seconds without changing behaviour.

// Before: tangled promise chain
function fetchUserData(userId) {
  return getUser(userId)
    .then(user => {
      return getOrders(user.id)
        .then(orders => {
          return { user, orders }
        })
    })
    .catch(err => console.error(err))
}

Ask Claude: "Refactor this to use async/await with proper error handling."

// After: flat and readable
async function fetchUserData(userId) {
  try {
    const user = await getUser(userId)
    const orders = await getOrders(user.id)
    return { user, orders }
  } catch (err) {
    console.error(err)
  }
}

Claude handles edge cases that trip up naive refactors: Promise.all() patterns that should stay parallel, .finally() blocks, error propagation differences, and callback-style Node APIs that need wrapping in promisify.

You can give it an entire file or module and ask it to convert everything in one pass — it'll flag any cases where the refactor might change behaviour and explain why.

Async/await isn't just syntactic sugar — cleaner async code means fewer subtle race conditions and much easier debugging.