Defer Await Until Needed

Move await operations into the branches where they're actually used to avoid blocking code paths that don't need them.

Incorrect (blocks both branches):

typescript

async function handleRequest(userId: string, skipProcessing: boolean) {
  const userData = await fetchUserData(userId)

  if (skipProcessing) {
    // Returns immediately but still waited for userData
    return {skipped: true}
  }

  // Only this branch uses userData
  return processUserData(userData)
}

Correct (only blocks when needed):

typescript

async function handleRequest(userId: string, skipProcessing: boolean) {
  if (skipProcessing) {
    // Returns immediately without waiting
    return {skipped: true}
  }

  // Fetch only when needed
  const userData = await fetchUserData(userId)
  return processUserData(userData)
}

Another example (early return optimization):

typescript

// Incorrect: always fetches permissions
async function updateResource(resourceId: string, userId: string) {
  const permissions = await fetchPermissions(userId)
  const resource = await getResource(resourceId)

  if (!resource) {
    return {error: 'Not found'}
  }

  if (!permissions.canEdit) {
    return {error: 'Forbidden'}
  }

  return await updateResourceData(resource, permissions)
}

// Correct: fetches only when needed
async function updateResource(resourceId: string, userId: string) {
  const resource = await getResource(resourceId)

  if (!resource) {
    return {error: 'Not found'}
  }

  const permissions = await fetchPermissions(userId)

  if (!permissions.canEdit) {
    return {error: 'Forbidden'}
  }

  return await updateResourceData(resource, permissions)
}

This optimization is especially valuable when the skipped branch is frequently taken, or when the deferred operation is expensive.