Unexpected `await` inside a loop. (no-await-in-loop)
JavascriptAsync AwaitJavascript Problem Overview
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)
Javascript Solutions
Solution 1 - Javascript
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);
});
Solution 2 - Javascript
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
Solution 3 - Javascript
I had a similar issue recently, I was getting lintting errors when trying to run an array of functions in a chain as apposed to asynchronously.
and this worked for me...
const myChainFunction = async (myArrayOfFunctions) => {
let result = Promise.resolve()
myArrayOfFunctions.forEach((myFunct) => {
result = result.then(() => myFunct()
})
return result
}
Solution 4 - Javascript
I am facing the same issue when I used await inside forEach loop. But I tried with recursive function call to iterate array.
const putDelay = (ms) =>
new Promise((resolve) => {
setTimeout(resolve, ms);
});
const myRecursiveFunction = async (events, index) => {
if (index < 0) {
return;
}
callAnotherFunction(events[index].activity, events[index].action, events[index].actionData);
await putDelay(1);
myRecursiveFunction(events, index - 1);
};