Unexpected `await` inside a loop. (no-await-in-loop)

问题

How Should I await for bot.sendMessage() inside of loop?
Maybe I Need await Promise.all But I Don't Know How Should I add to bot.sendMessage()

Code:

  const promise = query.exec();
  promise.then(async (doc) => {
    let count = 0;
    for (const val of Object.values(doc)) {
      ++count;
      await bot.sendMessage(msg.chat.id, `💬 ${count} and ${val.text}`, opts);
    }
  }).catch((err) => {
    if (err) {
      console.log(err);
    }
  });

Error:

[eslint] Unexpected `await` inside a loop. (no-await-in-loop)

回答1:

If you need to send each message one-at-a-time, then what you have is fine, and according to the docs, you can just ignore the eslint error like this:

const promise = query.exec();
promise.then(async doc => {
  /* eslint-disable no-await-in-loop */
  for (const [index, val] of Object.values(doc).entries()) {
    const count = index + 1;
    await bot.sendMessage(msg.chat.id, `💬 ${count} and ${val.text}`, opts);
  }
  /* eslint-enable no-await-in-loop */
}).catch(err => {
  console.log(err);
});

However, if there is no required order for sending the messages, you should do this instead to maximize performance and throughput:

const promise = query.exec();
promise.then(async doc => {
  const promises = Object.values(doc).map((val, index) => {
    const count = index + 1;
    return bot.sendMessage(msg.chat.id, `💬 ${count} and ${val.text}`, opts);
  });

  await Promise.all(promises);
}).catch(err => {
  console.log(err);
});

回答2:

Performing await inside loops can be avoided once iterations doesn't have dependency in most cases, that's why eslint is warning it here

You can rewrite your code as:

const promise = query.exec();
  promise.then(async (doc) => {
    await Promise.all(Object.values(doc).map((val, idx) => bot.sendMessage(msg.chat.id, `💬 ${idx + 1} and ${val.text}`, opts);)
  }).catch((err) => {
    if (err) {
      console.log(err);
    }
  });

If you still and to send one-after-one messages, your code is ok but eslint you keep throwing this error

来源：https://stackoverflow.com/questions/62380807/how-to-fix-unexpected-await-inside-a-loop-error-firebase-function