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アロー関数でasync/awaitしてみた備忘録(JavaScript)

Last updated at Posted at 2019-07-12

Qiitaで記事読んでてawaitいいじゃん使ってみよってなって書いたのが以下。例えばFirestoreからデータを取って来るコード。async/awaitをアロー関数で即時実行するように使うとこんな感じ。

(async () => {
  const querySnapshot = await db.collection('users').get()
  if (!querySnapshot.docs.length) {
    throw new Error('Empty!')
  }
  console.log(querySnapshot.docs[0].data())
})().catch(error => console.error(error))

このコードだと何も恩恵はないけど、非同期処理でありがちなpromise.thenがネストしちゃう時は効果バツグンだと思います。

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