I have some code that I cant get my head around, I am trying to return an array of object using a callback, I have a function that is returning the values and then pushing them into an array but I cant access this outside of the function, I am doing something stupid here but can't tell what ( I am very new to Node.JS )
for (var index in res.response.result) {
var marketArray = [];
(function () {
var market = res.response.result[index];
createOrUpdateMarket(market, eventObj , function (err, marketObj) {
marketArray.push(marketObj)
console.log('The Array is %s',marketArray.length) //Returns The Array is 1.2.3..etc
});
console.log('The Array is %s',marketArray.length) // Returns The Array is 0
})();
}
You have multiple issues going on here. A core issue is to gain an understanding of how asynchronous responses work and which code executes when. But, in addition to that you also have to learn how to manage multiple async responses in a loop and how to know when all the responses are done and how to get the results in order and what tools can best be used in node.js to do that.
Your core issue is a matter of timing. The createOrUpdateMarket() function is probably asynchronous. That means that it starts its operation when the function is called, then calls its callback sometime in the future. Meanwhile the rest of your code continues to run. Thus, you are trying to access the array BEFORE the callback has been called.
Because you cannot know exactly when that callback will be called, the only place you can reliably use the callback data is inside the callback or in something that is called from within the callback.
You can read more about the details of the async/callback issue here: Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference
To know when a whole series of these createOrUpdateMarket() operations are all done, you will have to code especially to know when all of them are done and you cannot rely on a simple for loop. The modern way to do that is to use promises which offer tools for helping you manage the timing of one or more asynchronous operations.
In addition, if you want to accumulate results from your for loop in marketArray, you have to declare and initialize that before your for loop, not inside your for loop. Here are several solutions:
Manually Coded Solution
var len = res.response.result.length;
var marketArray = new Array(len), cntr = 0;
for (var index = 0, index < len; index++) {
(function(i) {
createOrUpdateMarket(res.response.result[i], eventObj , function (err, marketObj) {
++cntr;
if (err) {
// need error handling here
}
marketArray[i] = marketObj;
// if last response has just finished
if (cntr === len) {
// here the marketArray is fully populated and all responses are done
// put your code to process the marketArray here
}
});
})(index);
}
Standard Promises Built Into Node.js
// make a version of createOrUpdateMarket that returns a promise
function createOrUpdateMarketAsync(a, b) {
return new Promise(function(resolve, reject) {
createOrUpdateMarket(a, b, function(err, marketObj) {
if (err) {
reject(err);
return;
}
resolve(marketObj);
});
});
}
var promises = [];
for (var i = 0; i < res.response.result.length; i++) {
promises.push(createorUpdateMarketAsync(res.response.result[i], eventObj));
}
Promise.all(promises).then(function(marketArray) {
// all results done here, results in marketArray
}, function(err) {
// an error occurred
});
Enhanced Promises with the Bluebird Promise library
The bluebird promise library offers Promise.map() which will iterate over your array of data and produce an array of asynchronously obtained results.
// make a version of createOrUpdateMarket that returns a promise
var Promise = require('bluebird');
var createOrUpdateMarketAsync = Promise.promisify(createOrUpdateMarket);
// iterate the res.response.result array and run an operation on each item
Promise.map(res.response.result, function(item) {
return createOrUpdateMarketAsync(item, eventObj);
}).then(function(marketArray) {
// all results done here, results in marketArray
}, function(err) {
// an error occurred
});
Async Library
You can also use the async library to help manage multiple async operations. In this case, you can use async.map() which will create an array of results.
var async = require('async');
async.map(res.response.result, function(item, done) {
createOrUpdateMarker(item, eventObj, function(err, marketObj) {
if (err) {
done(err);
} else {
done(marketObj);
}
});
}, function(err, results) {
if (err) {
// an error occurred
} else {
// results array contains all the async results
}
});
Related
I have code that looks something like this in javascript:
forloop {
//async call, returns an array to its callback
}
After ALL of those async calls are done, I want to calculate the min over all of the arrays.
How can I wait for all of them?
My only idea right now is to have an array of booleans called done, and set done[i] to true in the ith callback function, then say while(not all are done) {}
edit: I suppose one possible, but ugly solution, would be to edit the done array in each callback, then call a method if all other done are set from each callback, thus the last callback to complete will call the continuing method.
You haven't been very specific with your code, so I'll make up a scenario. Let's say you have 10 ajax calls and you want to accumulate the results from those 10 ajax calls and then when they have all completed you want to do something. You can do it like this by accumulating the data in an array and keeping track of when the last one has finished:
Manual Counter
var ajaxCallsRemaining = 10;
var returnedData = [];
for (var i = 0; i < 10; i++) {
doAjax(whatever, function(response) {
// success handler from the ajax call
// save response
returnedData.push(response);
// see if we're done with the last ajax call
--ajaxCallsRemaining;
if (ajaxCallsRemaining <= 0) {
// all data is here now
// look through the returnedData and do whatever processing
// you want on it right here
}
});
}
Note: error handling is important here (not shown because it's specific to how you're making your ajax calls). You will want to think about how you're going to handle the case when one ajax call never completes, either with an error or gets stuck for a long time or times out after a long time.
jQuery Promises
Adding to my answer in 2014. These days, promises are often used to solve this type of problem since jQuery's $.ajax() already returns a promise and $.when() will let you know when a group of promises are all resolved and will collect the return results for you:
var promises = [];
for (var i = 0; i < 10; i++) {
promises.push($.ajax(...));
}
$.when.apply($, promises).then(function() {
// returned data is in arguments[0][0], arguments[1][0], ... arguments[9][0]
// you can process it here
}, function() {
// error occurred
});
ES6 Standard Promises
As specified in kba's answer: if you have an environment with native promises built-in (modern browser or node.js or using babeljs transpile or using a promise polyfill), then you can use ES6-specified promises. See this table for browser support. Promises are supported in pretty much all current browsers, except IE.
If doAjax() returns a promise, then you can do this:
var promises = [];
for (var i = 0; i < 10; i++) {
promises.push(doAjax(...));
}
Promise.all(promises).then(function() {
// returned data is in arguments[0], arguments[1], ... arguments[n]
// you can process it here
}, function(err) {
// error occurred
});
If you need to make a non-promise async operation into one that returns a promise, you can "promisify" it like this:
function doAjax(...) {
return new Promise(function(resolve, reject) {
someAsyncOperation(..., function(err, result) {
if (err) return reject(err);
resolve(result);
});
});
}
And, then use the pattern above:
var promises = [];
for (var i = 0; i < 10; i++) {
promises.push(doAjax(...));
}
Promise.all(promises).then(function() {
// returned data is in arguments[0], arguments[1], ... arguments[n]
// you can process it here
}, function(err) {
// error occurred
});
Bluebird Promises
If you use a more feature rich library such as the Bluebird promise library, then it has some additional functions built in to make this easier:
var doAjax = Promise.promisify(someAsync);
var someData = [...]
Promise.map(someData, doAjax).then(function(results) {
// all ajax results here
}, function(err) {
// some error here
});
Checking in from 2015: We now have native promises in most recent browser (Edge 12, Firefox 40, Chrome 43, Safari 8, Opera 32 and Android browser 4.4.4 and iOS Safari 8.4, but not Internet Explorer, Opera Mini and older versions of Android).
If we want to perform 10 async actions and get notified when they've all finished, we can use the native Promise.all, without any external libraries:
function asyncAction(i) {
return new Promise(function(resolve, reject) {
var result = calculateResult();
if (result.hasError()) {
return reject(result.error);
}
return resolve(result);
});
}
var promises = [];
for (var i=0; i < 10; i++) {
promises.push(asyncAction(i));
}
Promise.all(promises).then(function AcceptHandler(results) {
handleResults(results),
}, function ErrorHandler(error) {
handleError(error);
});
You can use jQuery's Deferred object along with the when method.
deferredArray = [];
forloop {
deferred = new $.Deferred();
ajaxCall(function() {
deferred.resolve();
}
deferredArray.push(deferred);
}
$.when(deferredArray, function() {
//this code is called after all the ajax calls are done
});
You can emulate it like this:
countDownLatch = {
count: 0,
check: function() {
this.count--;
if (this.count == 0) this.calculate();
},
calculate: function() {...}
};
then each async call does this:
countDownLatch.count++;
while in each asynch call back at the end of the method you add this line:
countDownLatch.check();
In other words, you emulate a count-down-latch functionality.
This is the most neat way in my opinion.
Promise.all
FetchAPI
(for some reason Array.map doesn't work inside .then functions for me. But you can use a .forEach and [].concat() or something similar)
Promise.all([
fetch('/user/4'),
fetch('/user/5'),
fetch('/user/6'),
fetch('/user/7'),
fetch('/user/8')
]).then(responses => {
return responses.map(response => {response.json()})
}).then((values) => {
console.log(values);
})
Use an control flow library like after
after.map(array, function (value, done) {
// do something async
setTimeout(function () {
// do something with the value
done(null, value * 2)
}, 10)
}, function (err, mappedArray) {
// all done, continue here
console.log(mappedArray)
})
In Node.js you can use async/await to control the async flow
async/await is supported in Node.js 7.6
util function to promisify callback is supported in Node.js v8
Sample Code:
const foo = async () => {
try {
const ids = [100, 101, 102];
const fetchFromExternalApi = util.promisify(fetchFromExternalApiCallback);
const promises = ids.map((id) => fetchFromExternalApi(id));
const dataList = await Promise.resolve(promises); // dataList is an array
return dataList;
} catch (err) {
// error handling
}
};
I see several response with Promise.all(), but this function stop if any promise generate an exception...
The best solution in 2022 is Promise.allSettled() (documentation here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/allSettled
A quick sample:
const allPromises = [];
for (r in records) {
const promise = update_async(r);
allPromises.push(promise);
};
await Promise.allSettled(allPromises);
At the end, you obtain with allPromises an array with the result of each promise:
when ok --> {status: “fulfilled”, value: xxx }
when error --> {status: "rejected", reason: Error: an error}
I understand using promises in simple scenarios but currently really confused on how to implement something when using a for loop and some updates to local sqlite database.
Code is as follows
surveyDataLayer.getSurveysToUpload().then(function(surveys) {
var q = $q.defer();
for (var item in surveys) {
var survey = surveys[item];
// created as a closure so i can pass in the current item due to async process
(function(survey) {
ajaxserviceAPI.postSurvey(survey).then(function(response) {
//from response update local database
surveyDataLayer.setLocalSurveyServerId(survey, response.result).then(function() {
q.resolve; // resolve promise - tried only doing this when last record also
})
});
})(survey) //pass in current survey used to pass in item into closure
}
return q.promise;
}).then(function() {
alert('Done'); // This never gets run
});
Any help or assistance would be appreciated. I'm probably struggling on how best to do async calls within loop which does another async call to update and then continue once completed.
at least promises have got me out of callback hell.
Cheers
This answer will get you laid at JS conferences (no guarantees though)
surveyDataLayer.getSurveysToUpload().then(function(surveys) {
return Promise.all(Object.keys(surveys).map(function(key) {
var survey = surveys[key];
return ajaxserviceAPI.postSurvey(survey).then(function(response){
return surveyDataLayer.setLocalSurveyServerId(survey, response.result);
});
}));
}).then(function() {
alert('Done');
});
This should work (explanations in comments):
surveyDataLayer.getSurveysToUpload().then(function(surveys) {
// array to store promises
var promises = [];
for (var item in surveys) {
var survey = surveys[item];
// created as a closure so i can pass in the current item due to async process
(function(survey) {
var promise = ajaxserviceAPI.postSurvey(survey).then(function(response){
//returning this promise (I hope it's a promise) will replace the promise created by *then*
return surveyDataLayer.setLocalSurveyServerId(survey, response.result);
});
promises.push(promise);
})(survey); //pass in current survey used to pass in item into closure
}
// wait for all promises to resolve. If one fails nothing resolves.
return $q.all(promises);
}).then(function() {
alert('Done');
});
Awesome tutorial: http://ponyfoo.com/articles/es6-promises-in-depth
You basically want to wait for all of them to finish before resolving getSurveysToUpload, yes? In that case, you can return $q.all() in your getSurveysToUpload().then()
For example (not guaranteed working code, but you should get an idea):
surveyDataLayer.getSurveysToUpload().then(function(surveys) {
var promises = [];
// This type of loop will not work in older IEs, if that's of any consideration to you
for (var item in surveys) {
var survey = surveys[item];
promises.push(ajaxserviceAPI.postSurvey(survey));
}
var allPromise = $q.all(promises)
.then(function(responses) {
// Again, we want to wait for the completion of all setLocalSurveyServerId calls
var promises = [];
for (var index = 0; index < responses.length; index++) {
var response = responses[index];
promises.push(surveyDataLayer.setLocalSurveyServerId(survey, response.result));
}
return $q.all(promises);
});
return allPromise;
}).then(function() {
alert('Done'); // This never gets run
});
I have this code:
var queue = [];
var allParserd = [];
_.each(webs, function (web) {
queue.push(function () {
WebsitesUtils.parseWebsite(web, function (err, parsed) {
allParserd.push(parsed);
});
});
});
Promise.all(queue).then(function (data) {
console.log(allParserd);
});
Basically I need to fetch all my webs and be sure to give the result after that every parsing is done. the function parseWebsite return the correct data, but in this way is not called and allParsed return just as an empty array. I'm sure that I miss some things, I've started to use the promises just from some days.
If you need some more information just tell me.
P.s.
I want that all the functions to start at the same time; I don't want to wait for each one response for going forward.
Tagged with Bluebird so let's use it:
First, let's convert your callback API to promises:
Promise.promisifyAll(WebsitesUtils);
Now, let's use .map to map every item in webs to it being parsed parseWebsite:
Promise.map(webs, function(item){
return WebsitesUtils.parseWebsiteAsync(item); // note the suffix
}).then(function(results){
// all the results are here.
}).catch(function(err){
// handle any errors
});
As you can see - this is trivial to do with Bluebird.
Promise.all doesn't take a queue of functions to execute. It expects an array of promises which represent the results of the many concurrently running (still pending) requests.
The first step is to have a function that actually returns a promise, instead of only executing a callback. We can use
function parseWebsite(web) {
return new Promise(function(fulfill, reject) {
WebsitesUtils.parseWebsite(web, function (err, parsed) {
if (err)
reject(err);
else
fulfill(parsed);
});
});
}
or simply use promisification that does this generically:
var parseWebsite = Promise.promisify(WebsitesUtils.parseWebsite, WebsitesUtils);
Now we can go to construct our array of promises by calling that function for each site:
var promises = [];
_.each(webs, function (web) {
promises.push(parseWebsite(web));
});
or just
var promises = _.map(webs, parseWebsite);
so that in the end we can use Promise.all, and get back our allParsed array (which even is in the same order as webs was!):
Promise.all(promises).then(function(allParsed) {
console.log(allParsed);
});
Bluebird even provides a shortcut function so you don't need promises:
Promise.map(webs, parseWebsite).then(function(allParsed) {
console.log(allParsed);
});
Here's how might do it with async:
var async = require('async');
var webs = ...
async.map(webs, function(web, callback) {
WebsitesUtils.parseWebsite(web, callback);
}, function(err, results) {
if (err) throw err; // TODO: handle errors better
// `results` contains all parsed results
});
and if parseWebsite() isn't a prototype method dependent on WebsitesUtils then you could simplify it further:
async.map(webs, WebsitesUtils.parseWebsite, function(err, results) {
if (err) throw err; // TODO: handle errors better
// `results` contains all parsed results
});
I am trying to solve an exam problem, so I cannot post my exam code as it is. So I have simplified such that it addresses the core concept that I do not understand. Basically, I do not know how to slow down node's asynchronous execution so that my mongo code can catch up with it. Here is the code:
MongoClient.connect('mongodb://localhost:27017/somedb', function(err, db) {
if (err) throw err;
var orphans = [];
for (var i; i < 100000; i++) {
var query = { 'images' : i };
db.collection('albums').findOne(query, function(err, doc_album) {
if(err) throw err;
if (doc_album === null) {
orphans.push(i);
}
});
}
console.dir(orphans.length);
return db.close();
});
So I am trying to create an array of those images who do not match my query criteria. I end up with a orphans.length value of 0 since Node does not wait for the callbacks to finish. How can I modify the code such that the callbacks finish executing before I count the number of images in the array that did not meet my query criteria?
Thanks in advance for your time.
Bharat
I assume you want to do 100000 parallel DB calls. To "wait" 10000 calls completion in each call callback we increase finished calls counter and invoke main callback when last one finished. Note that very common mistake here is to use for loop variable as a closure inside callback. This does not work as expected as all 10000 handlers scheduled first and by the time first is executed loop variable is of the same, maximum value.
function getOrphans(cb) {
MongoClient.connect('mongodb://localhost:27017/somedb', function(err, db) {
if (err) cb(err);
var orphans = [];
var numResponses = 0;
var maxIndex = 100000
for (var i = 0; i < maxIndex; i++) {
// problem: by the time you get reply "i" would be 100000.
// closure variable changed to function argument:
(function(index) {
var query = { 'images' : index };
db.collection('albums').findOne(query, function(err, doc_album) {
numResponses++;
if(err) cb(err);
if (doc_album === null) {
orphans.push(index);
}
if (numResponses == maxIndex) {
db.close();
cb(null, orphans);
}
});
})(i); // this is "immediately executed function
}
});
}
getOrphans(function(err, o) {
if (err)
return console.log('error:', err);
console.log(o.length);
});
Im not suggesting this is the best way to handle this specific problem in Mongo, but if you need to wait to the DB to reply before continuing then just use the callback to start next request.
This is not obvious at first, but you can refer to the result processing function inside the function itself:
var i = 0;
var mycback = function(err, doc_album) {
// ... process i-th result ...
if (++i < 100000) {
db.collections("album").findOne({'images': i}, mycback);
} else {
// request is complete, "return" result
result_cback(null, res);
}
};
db.collections('album').findOne({'images': 0}, mycback);
This also means that your function itself will be async (i.e. will want a result_cback parameter to call with the result instead of using return).
Writing a sync function that calls an async one is just not possible.
You cannot "wait" for an event in Javascript... you must set up an handler for the result and then terminate.
Waiting for an event is done in event-based processing by writing a "nested event loop" and this is for example how message boxes are handled in most GUI frameworks. This is a capability that Javascript designers didn't want to give to programmers (not really sure why, though).
Since you know it does not wait for the call to come back. You can do the console.dir inside your callback function, this should work (although I haven't tested it)
db.collection('albums').findOne(query, function(err, doc_album) {
if(err) throw err;
if (doc_album === null) {
orphans.push(i);
}
console.dir(orphans.length);
});
You don't need to slow anything down. If you are simply trying to load 100,000 images from the albums collection, you could consider using the async framework. This will let you assign tasks until the job is complete.
Also, you probably don't want request 100,000 records one-by-one. Instead, you probably want to page them.
I have code that looks something like this in javascript:
forloop {
//async call, returns an array to its callback
}
After ALL of those async calls are done, I want to calculate the min over all of the arrays.
How can I wait for all of them?
My only idea right now is to have an array of booleans called done, and set done[i] to true in the ith callback function, then say while(not all are done) {}
edit: I suppose one possible, but ugly solution, would be to edit the done array in each callback, then call a method if all other done are set from each callback, thus the last callback to complete will call the continuing method.
You haven't been very specific with your code, so I'll make up a scenario. Let's say you have 10 ajax calls and you want to accumulate the results from those 10 ajax calls and then when they have all completed you want to do something. You can do it like this by accumulating the data in an array and keeping track of when the last one has finished:
Manual Counter
var ajaxCallsRemaining = 10;
var returnedData = [];
for (var i = 0; i < 10; i++) {
doAjax(whatever, function(response) {
// success handler from the ajax call
// save response
returnedData.push(response);
// see if we're done with the last ajax call
--ajaxCallsRemaining;
if (ajaxCallsRemaining <= 0) {
// all data is here now
// look through the returnedData and do whatever processing
// you want on it right here
}
});
}
Note: error handling is important here (not shown because it's specific to how you're making your ajax calls). You will want to think about how you're going to handle the case when one ajax call never completes, either with an error or gets stuck for a long time or times out after a long time.
jQuery Promises
Adding to my answer in 2014. These days, promises are often used to solve this type of problem since jQuery's $.ajax() already returns a promise and $.when() will let you know when a group of promises are all resolved and will collect the return results for you:
var promises = [];
for (var i = 0; i < 10; i++) {
promises.push($.ajax(...));
}
$.when.apply($, promises).then(function() {
// returned data is in arguments[0][0], arguments[1][0], ... arguments[9][0]
// you can process it here
}, function() {
// error occurred
});
ES6 Standard Promises
As specified in kba's answer: if you have an environment with native promises built-in (modern browser or node.js or using babeljs transpile or using a promise polyfill), then you can use ES6-specified promises. See this table for browser support. Promises are supported in pretty much all current browsers, except IE.
If doAjax() returns a promise, then you can do this:
var promises = [];
for (var i = 0; i < 10; i++) {
promises.push(doAjax(...));
}
Promise.all(promises).then(function() {
// returned data is in arguments[0], arguments[1], ... arguments[n]
// you can process it here
}, function(err) {
// error occurred
});
If you need to make a non-promise async operation into one that returns a promise, you can "promisify" it like this:
function doAjax(...) {
return new Promise(function(resolve, reject) {
someAsyncOperation(..., function(err, result) {
if (err) return reject(err);
resolve(result);
});
});
}
And, then use the pattern above:
var promises = [];
for (var i = 0; i < 10; i++) {
promises.push(doAjax(...));
}
Promise.all(promises).then(function() {
// returned data is in arguments[0], arguments[1], ... arguments[n]
// you can process it here
}, function(err) {
// error occurred
});
Bluebird Promises
If you use a more feature rich library such as the Bluebird promise library, then it has some additional functions built in to make this easier:
var doAjax = Promise.promisify(someAsync);
var someData = [...]
Promise.map(someData, doAjax).then(function(results) {
// all ajax results here
}, function(err) {
// some error here
});
Checking in from 2015: We now have native promises in most recent browser (Edge 12, Firefox 40, Chrome 43, Safari 8, Opera 32 and Android browser 4.4.4 and iOS Safari 8.4, but not Internet Explorer, Opera Mini and older versions of Android).
If we want to perform 10 async actions and get notified when they've all finished, we can use the native Promise.all, without any external libraries:
function asyncAction(i) {
return new Promise(function(resolve, reject) {
var result = calculateResult();
if (result.hasError()) {
return reject(result.error);
}
return resolve(result);
});
}
var promises = [];
for (var i=0; i < 10; i++) {
promises.push(asyncAction(i));
}
Promise.all(promises).then(function AcceptHandler(results) {
handleResults(results),
}, function ErrorHandler(error) {
handleError(error);
});
You can use jQuery's Deferred object along with the when method.
deferredArray = [];
forloop {
deferred = new $.Deferred();
ajaxCall(function() {
deferred.resolve();
}
deferredArray.push(deferred);
}
$.when(deferredArray, function() {
//this code is called after all the ajax calls are done
});
You can emulate it like this:
countDownLatch = {
count: 0,
check: function() {
this.count--;
if (this.count == 0) this.calculate();
},
calculate: function() {...}
};
then each async call does this:
countDownLatch.count++;
while in each asynch call back at the end of the method you add this line:
countDownLatch.check();
In other words, you emulate a count-down-latch functionality.
This is the most neat way in my opinion.
Promise.all
FetchAPI
(for some reason Array.map doesn't work inside .then functions for me. But you can use a .forEach and [].concat() or something similar)
Promise.all([
fetch('/user/4'),
fetch('/user/5'),
fetch('/user/6'),
fetch('/user/7'),
fetch('/user/8')
]).then(responses => {
return responses.map(response => {response.json()})
}).then((values) => {
console.log(values);
})
Use an control flow library like after
after.map(array, function (value, done) {
// do something async
setTimeout(function () {
// do something with the value
done(null, value * 2)
}, 10)
}, function (err, mappedArray) {
// all done, continue here
console.log(mappedArray)
})
In Node.js you can use async/await to control the async flow
async/await is supported in Node.js 7.6
util function to promisify callback is supported in Node.js v8
Sample Code:
const foo = async () => {
try {
const ids = [100, 101, 102];
const fetchFromExternalApi = util.promisify(fetchFromExternalApiCallback);
const promises = ids.map((id) => fetchFromExternalApi(id));
const dataList = await Promise.resolve(promises); // dataList is an array
return dataList;
} catch (err) {
// error handling
}
};
I see several response with Promise.all(), but this function stop if any promise generate an exception...
The best solution in 2022 is Promise.allSettled() (documentation here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/allSettled
A quick sample:
const allPromises = [];
for (r in records) {
const promise = update_async(r);
allPromises.push(promise);
};
await Promise.allSettled(allPromises);
At the end, you obtain with allPromises an array with the result of each promise:
when ok --> {status: “fulfilled”, value: xxx }
when error --> {status: "rejected", reason: Error: an error}