common promise mishaps

example.js

// bad you're waiting for the first result but the second and third request don't need anything from the NAME query
// sequential async actions :do_not_want:
async fucntion waterfall(db) {
  const name = await db.query(NAME)
  const open = await db.query(IS_OPEN)
  const welcomeMessage = await db.query(WELCOME_MESSAGE)
  return { name, open, welcomeMessage }
}

// better there are no depenecies so start them all off at the same time
// concurrent :thinking_face: LGTM
async function concurrent(db) {
  const [name, open, welcomeMessage] = await Promise.all([
    db.query(NAME),
    db.query(IS_OPEN),
    db.query(WELCOME_MESSAGE)
  ])
  return { name, open, welcomMessage }
}

// bad you don't need to await side effects that have no impact on execution flow, ie tracking
async function blockOnTracking(user, db) {
  const record = await db.getSharedRecord(SHARED_RECORD)
  await db.insertRowOnTrackingTable(user)
  return record
}

// better, you can just fire off the action and return the data to the user more quickly
async function blockOnTracking(user, db) {
  const record = await db.getSharedRecord(SHARED_RECORD)
  // we need to handle the error or it might break your app potentially with an unhaldled promise rejection
  db.insertRowOnTrackingTable(user).catch(handleError)
  return record
}