Async/awaitはforEach非同期ループを処理できませんか?!

結論:Async/awaitはArrayである。prototype.foreachを使用する場合は非同期処理はできません。

const urls = [
  'https://lotsofinformation.com/loop/1',
  'https://lessinformation.com/loop/2',
  'https://lessinformation.com/loop/3'
];

async function loops() {
  await urls.forEach(async (url, idx) => { 
    const loop = await fetch(url);
    console.log(`Fetch loop ${idx+1}`);
  });
  
  console.log('Done!');
}

loops();

/* 결과:
Done!
Fetch loop 2
Fetch loop 1
Fetch loop 3
*/

質問:

ソリューション:

for...使用

const urls = [
  'https://lotsofinformation.com/loop/1',
  'https://lessinformation.com/loop/2',
  'https://lessinformation.com/loop/3'
];

async function loops() {
  for (const [idx, url] of urls.entries()) { 
    const loop = await fetch(url);
    console.log(`Fetch loop ${idx+1}`);
  }
  
  console.log('Done!');
}

loops();

/* 결과:
Fetch loop 1
Fetch loop 2
Fetch loop 3
Done!
*/