Related
I am trying to run a function 4 times (with different parameters) asynchronously with a Promise.all. This snippet runs, however it will only run each 'loopGridValidate' function in order synchronously. I have replaced the loopGridValidate function with the logic from this https://www.javascripttutorial.net/es6/javascript-promise-all/ tutorial and the Promise.all returns what is expected. I'm not sure what I am missing... The loop function is async, everything is set up correctly in the promise all (I have also split out the new promise's into 'const p1 = new Promise' and have the same effect as the code snippet below)
function validateCells() {
var grid = $("#NonStartUpGrid").data("kendoGrid");
var rows = grid.tbody.find("tr"); //rows from excel sheet
var valid = true;
var errorCount = 0;
var rowSec1 = Math.floor(rows.length * .25)
var rowSec2 = Math.floor(rows.length * .5)
var rowSec3 = Math.floor(rows.length * .75)
Promise.all([new Promise((resolve, reject) => { resolve(loopGridValidate(rows, grid, errorCount, 0, rowSec1, valid)); })
, new Promise((resolve, reject) => { resolve(loopGridValidate(rows, grid, errorCount, rowSec1 + 1, rowSec2, valid)); })
, new Promise((resolve, reject) => { resolve(loopGridValidate(rows, grid, errorCount, rowSec2 + 1, rowSec3, valid)); })
, new Promise((resolve, reject) => { resolve(loopGridValidate(rows, grid, errorCount, rowSec3 + 1, rows.length - 1, valid)); })
]).then(results => { const total = results.reduce((a, b) => a + b, 0) });
return errorCount;
};
async function loopGridValidate(rows, grid, errorCount, begin, end, valid) {
console.log(begin);
for (var i = begin; i <= end; i++) {
var rowModel = grid.dataItem(rows[i]);
if (rowModel) {
console.log(i);
var colCells = $(rows[i]).find("td[role=gridcell]");
for (var j = 0; j < colCells.length; j++) {
//custom logic
}
}
}
scrollToTop(grid)
if (valid) {
$("#SubmitGrid").prop("disabled", "");
}
$("#loading").prop("hidden", "hidden");
return errorCount;
}
Here is a fiddle to show a basic example of what I am talking about that is happening. If you click the button you will see in the console, the functions are ran synchronously, instead of asynchronously(the i values would be mixed up instead of in order) https://jsfiddle.net/tap16fbo/
Promise body is synchronous, try using setTimeout. For more information
function loop(begin, end, results) {
setTimeout(() => {
for (var i = begin; i <= end; i++) {
console.log(i);
}
results();
}, Math.random() * 1000)
}
function BeginPromise() {
const p1 = new Promise((resolve, reject) => {
loop(0, 100, resolve)
});
const p2 = new Promise((resolve, reject) => {
loop(110, 200, resolve)
});
const p3 = new Promise((resolve, reject) => {
loop(210, 300, resolve)
});
return Promise.all([p1, p2, p3]).then(() => console.log('done'))
}
I suspect I've fundementally misunderstood Javascript promises, any ideas?
I have a pretty function that queries a database containing music that looks like this:
function searchDatabaseForTrack(query,loadedResults){
loadedResults = loadedResults || [];
desiredResults = 100;
if (loadedResults.length < desiredResults) {
try {
databaseApi.searchTracks(query, {"offset":loadedResults.length, "limit":"50", }).then(function(data){
i=0
if (data.tracks.items.length == 0) {
console.log(`Already loaded all ${loadedResults.length} tracks!`)
console.log(loadedResults)
return loadedResults;
}
else {
for (thing in data.tracks.items){
loadedResults.push(data.tracks.items[i]);
i=i+1;
}
console.log(loadedResults.length, " tracks collected");
searchDatabaseForTrack(query,loadedResults)
}
});
} catch(err) {
console.log("ERROR!", err)
console.log(loadedResults)
return loadedResults;
}
} else {
console.log(loadedResults)
return loadedResults;
}
}
And then a bit later, I try to call and use the data retrieved.
function getArtistTracks(artistName){
searchDatabaseForTrack(artistName).then(function(data){
console.log(songs);
songs.sort(function(a,b){
var c = new Date(a.track.album.release_date);
var d = new Date(b.track.album.release_date);
return d-c;
});
console.log("songs", songs);
var newsongs=[];
i=0
for (song in songs) {
newsongs.push(songs[i].track.uri);
i++
};
return newsongs;
});
}
What I'm trying to do is get the second function "getArtistTracks" to wait for the completion of the query in the first function. Now I could just call the databaseApi.searchTracks directly, but there's a limit of 50 tracks returned per result — which kind of screws me over.
searchDatabaseForTrack().then(...) shouldn't work since searchDatabaseForTrack() doesn't return a promise, so you can either return a promise or use an async function.
instead of a recursive function, you could simply call databaseApi in a for loop,
the desiredResult should be an argument and not hardcoded in the function,
async function searchDatabaseForTrack(query, desiredResults){
let loadedResults = [], data, currOffset = 0;
const iterations = Math.ceil(desiredResults / 50);
for(let n = 0 ; n < iterations; n++){
cuurOffset = n * 50;
data = await databaseApi.searchTracks(query, {"offset":currOffset, "limit":"50", });
if (data.tracks.items.length == 0) {
console.log(`Already loaded all ${loadedResults.length} tracks!`)
console.log(loadedResults)
return loadedResults;
}
else {
loadedResults = loadedResults.concat(data.tracks.items);
console.log(loadedResults.length, " tracks collected");
}
}
return loadedResults;
}
the rest should be fine as long as you add .catch() to handle errors ( as mentionned in previous answer ) which are thrown automatically without the need of the try/catch block :
function getArtistTracks(artistName, 100){
searchDatabaseForTrack(artistName).then((songs) => {
// your previous code
})
.catch((err) => {
// handle error
});
});
Have searchDatabaseForTrack use Promise.all to return the loadedResults after all results have been gotten. Also, make sure not to implicitly create global variables as you're doing with thing. For example, try something like this:
async function searchDatabaseForTrack(query) {
const desiredResults = 100;
const trackPromises = Array.from(
({ length: Math.ceil(desiredResults / 50) }),
(_, i) => {
const offset = i * 50;
return databaseApi.searchTracks(query, { offset, limit: 50 });
}
);
const itemChunks = await Promise.all(trackPromises);
const loadedResults = itemChunks.reduce((a, { tracks: { items }}) => (
[...a, ...items]
), []);
return loadedResults;
};
and
searchDatabaseForTrack(artistName).then((loadedResults) => {
// do stuff with loadedResults
})
.catch((err) => {
console.log("ERROR!", err)
// handle error
});
I am trying to get a bunch of ID's from an API and then form a sequence of requests which would make further calls to an API to fetch some parameters. These would be totaled and i expect the output results to be pushed as JSON array.
The problem is REST call is async and i've put a promise but not sure when to resolve the promise back to the calling function, the rest call some times take a second or 2 to respond back.
I would like know at what point can i resolve the promise or how to know when the totals have been computed ?
The Route
app.get("/sonar/:x_id",function(req,resp) {
getRestSonar(req.params.x_id).then(function (fromResolve) {
resp.send(fromResolve);
});
});
The function with promise which makes the rest call loops
var getRestSonar = function(requestX) {
return new Promise(function(resolve,reject) {
var unirest = require("unirest");
var reqx = unirest("GET", "http://sonarqubexxServer/api/projects");
var outputJson = {
table: []
};
reqx.end(function (res) {
if (res.error) throw new Error(res.error);
// console.log(res.body);
var result = res.body;
//var needle = req.params.csi_id;
var needle = requestX;
var TotalDuplicateLines = 0;
var TotalBugs = 0;
var TotalNcloc = 0;
var TotalCodeSmells = 0;
var TotalVulnerabilities = 0;
for (var i=0;i<result.length;i++) {
if (result[i].nm.indexOf(needle) !== -1) {
console.log(result[i].k);
var queryUrl = "http://sonarqubexxServer/api/resources?resource="+result[i].k+"&metrics=code_smells,bugs,vulnerabilities,ncloc,coverage,duplicated_lines&format=json"
console.log(queryUrl);
var subrequest = unirest("GET",queryUrl);
subrequest.end(function (resXX) {
if (resXX.error);
var resXXResult = resXX.body;
for (var i=0;i<resXXResult.length;i++) {
// var duplicateData = resXXResult[0].msr.filter(item => item.key == 'duplicated_lines');
resXXResult[i].msr.forEach(m => {
if (m.key === 'duplicated_lines') {
console.log('Duplicated Lines ' + m.val);
TotalDuplicateLines += m.val;
}
else if(m.key === 'bugs' ) {
console.log('Bugs ' + m.val);
TotalBugs += m.val;
}
else if(m.key === 'ncloc' ) {
console.log('Lines of Code ' + m.val);
TotalNcloc += m.val;
}
else if(m.key === 'code_smells' ) {
console.log('Code Smells ' + m.val);
TotalCodeSmells += m.val;
}
else if(m.key === 'vulnerabilities' ) {
console.log('Vulnerabilities ' + m.val);
TotalVulnerabilities += m.val;
outputJson.table.push({totduplines:TotalDuplicateLines},{totVul:TotalVulnerabilities});
}
});
console.log("Iam here with I :: " + i);
if (i === (resXXResult.length - 1)) {
//Should i resolve here makes no sense
console.log("Resolved the promise now..");
}
//The for ends here
}
// I see this is a bad place to resolve..
resolve(outputJson);
});
}
}
});
});
}
EDIT : As suggested in the comments, split the calls into smaller
sections
Now, i fetch the api calls seperatly create an array out of it, then use promises to call back to the API ? how do i resolve each call by looping over it ?
When i try to loop it always resolves request[0] and then comes out of the promise, how can i create a promise array and wait for them to complete ?
app.get("/sonar/:csi_id",function(req,resp) {
var collectiveResult = [];
getRestSonar(req.params.csi_id).then(function (fromResolve) {
return splitReqUrl(fromResolve);
}).then(function(fromSplitUrl) {
console.log("I am from split url ::::" + fromSplitUrl);
return getSubSonarProperties(fromSplitUrl);
}).then(function(fromsubSonar) {
collectiveResult.push(fromsubSonar);
console.log("+++++++++++++++++++++++++++");
console.log(fromsubSonar);
resp.send(collectiveResult);
});
});
var getSubSonarProperties = function(getUrl) {
return new Promise(function(resolve,reject) {
var getSubRest = require("unirest");
console.log("Attempting to GET " + getUrl);
var req = getSubRest("GET",getUrl);
var outputJson = {
table: []
}
var TotalDuplicateLines = 0;
var TotalBugs = 0;
var TotalNcloc = 0;
var TotalCodeSmells = 0;
var TotalVulnerabilities = 0;
req.end(function (res) {
if (res.error);
var resXXResult = res.body;
resolve(resXXResult);
});
});
}
var splitReqUrl = function(request) {
return new Promise(function(resolve,reject) {
resolve(request[1]);
//for(var i=0; i< request.length; i++) {
// resolve(request[i]);
//}
});
}
var getRestSonar = function(requestX) {
return new Promise(function(resolve,reject) {
var unirest = require("unirest");
var reqx = unirest("GET", "http://sonarqubexxx/api/projects");
var outputJson = {
table: []
};
reqx.end(function (res) {
if (res.error) throw new Error(res.error);
// console.log(res.body);
var result = res.body;
//var needle = req.params.csi_id;
var needle = requestX;
var queryArray = [];
for (var i=0;i<result.length;i++) {
if (result[i].nm.indexOf(needle) !== -1) {
console.log(result[i].k);
var queryUrl = "http://sonarxxx/api/resources?resource="+result[i].k+"&metrics=code_smells,bugs,vulnerabilities,ncloc,coverage,duplicated_lines&format=json"
//console.log(queryUrl);
queryArray.push(queryUrl);
}
if (i === (result.length - 1)) {
resolve(queryArray);
}
}
});
});
}
Problem
First of all the problem with your solution is that you're trying to make everything inside a single big new Promise(...) creator.
Even if you manage to make that work it's still a common anti-pattern as Promises are made to be chained using the .then(...) method.
As pointed out by Roamer-1888 there oughta be a fork of unirest that handles Promises directly instead of requiring callbacks as in your example, but let's stick with your version of unirest here.
Solution
So what you need to be doing is create a Promise chain to handle the different steps of your code and pass the results down the chain.
Your steps seem to be:
Make the first call to retrieve initial results.
Filter the results based on the requestX input.
For each item left, make several calls to obtain more data.
Put everything back into an outputJson object.
Basically the only async steps are 1 and 3, but it might be ok to add a third step to build your outputJson and pass it downstream.
So let's start with the first step.
1. Make the first call
In the first link of the Promise chain we need to retrieve the initial results with your first unirest call:
new Promise((resolve, reject) => {
unirest("GET", "http://sonarqubexxServer/api/projects")
.end((res) => {
if (res.error) {
reject(res.error);
} else {
resolve(res.body);
}
});
})
See in this example I already checked if the response contains an error and fired a rejection in that case, otherwise I resolve the promise with the body (the data we need).
The Promise we created above will throw an error if the request fails, and will downstream the body of the response if everything goes fine.
2. Filtering and Sub-calls
Now then we can go ahead and use the full potential of Promises with the .then(...) method:
new Promise((resolve, reject) => {
unirest("GET", "http://sonarqubexxServer/api/projects")
.end((res) => {
if (res.error) {
reject(res.error);
} else {
resolve(res.body);
}
});
}).then((results) => {
results = results.filter((result) => {
return result.nm.indexOf(request) != -1;
});
return Promise.all(results.map((result) => {
return new Promise((resolve, reject) => {
var queryUrl = "http://sonarqubexxServer/api/resources?resource=" + result.k + "&metrics=code_smells,bugs,vulnerabilities,ncloc,coverage,duplicated_lines&format=json"
unirest("GET", queryUrl)
.end((res) => {
if (res.error) {
reject(res.error);
} else {
resolve(res.body);
}
});
})
}))
})
In this step I used some Array methods to make the code cleaner and Promise.all to handle several promises together.
Array.filter is a method which iterates an array and checks for each item if it should be kept in the filtered output or not. So, in your case, we want to keep only those items where result.nm.indexOf(request) != -1.
Array.map is a method which iterates an array and converts each item to something else. Basically the function you provide takes each item as input, converts it to something else and then replaces this new value to the old one in the output array.
Finally Promise.all accepts an array of Promises and returns a Promise itself. This returned Promise will resolve when all the given Promises resolve and will pass downstream an array which items are the results of each single Promise.
So by writing Promise.all(results.map((results) => { return new Promise(...) })) we convert each result in the results array into a Promise that executes the result-specific call and put it into the output array of Promises which is fed to Promise.all so they get executed at once.
3. Build the outputJSON
Now the Promise chain outputs the result of Promise.all which is an array of all the results of each Promise, which are the results of each sub-call.
We can then simply take the downstream data and use your nested iterations to build the outputJSON to be passed downstream:
new Promise((resolve, reject) => {
unirest("GET", "http://sonarqubexxServer/api/projects")
.end((res) => {
if (res.error) {
reject(res.error);
} else {
resolve(res.body);
}
});
}).then((results) => {
results = results.filter((result) => {
return result.nm.indexOf(request) != -1;
});
return Promise.all(results.map((result) => {
return new Promise((resolve, reject) => {
var queryUrl = "http://sonarqubexxServer/api/resources?resource=" + result.k + "&metrics=code_smells,bugs,vulnerabilities,ncloc,coverage,duplicated_lines&format=json"
unirest("GET", queryUrl)
.end((res) => {
if (res.error) {
reject(res.error);
} else {
resolve(res.body);
}
});
})
}))
}).then((allResults) => {
var TotalDuplicateLines = 0;
var TotalBugs = 0;
var TotalNcloc = 0;
var TotalCodeSmells = 0;
var TotalVulnerabilities = 0;
var outputJson = {
table: []
};
for (var i = 0; i < allResults; i++) {
for (var j = 0; j < allResults[i].length; j++) {
allResults[i][j].msr.forEach(m => {
if (m.key === 'duplicated_lines') {
TotalDuplicateLines += m.val;
}
else if (m.key === 'bugs') {
TotalBugs += m.val;
}
else if (m.key === 'ncloc') {
TotalNcloc += m.val;
}
else if (m.key === 'code_smells') {
TotalCodeSmells += m.val;
}
else if (m.key === 'vulnerabilities') {
TotalVulnerabilities += m.val;
outputJson.table.push({ totduplines: TotalDuplicateLines }, { totVul: TotalVulnerabilities });
}
});
}
}
return outputJson;
})
If your return this long Promise chain in your getRestSonar(request) function, then you could write getRestSonar(request).then((outputJson) => { ... do something with your outputJson ... })
Well I understand that one would have to return a promise, and not the result of a promise to pass promises around.
However I seem to be unable to implement this, say I have a member method like:
CreateNextBatch() {
this.orders.clear();
let maxNum = this.maxNum;
let counter = this.orderCounter;
let CreateThem = (counter, r) => {
if (r >= 0) {
//Order.find() finds an entry in a database
Order
.find({orderNr: counter.fullNumber()})
.then(function(orders) {
console.log("created order " + counter.fullNumber().toString());
let num = r;
if (orders.length === 0) {
this.OpenOrder(counter.fullNumber());
//adds order to this.orders
num -= 1;
}
counter.nextNumber();
return CreateThem(counter, num);
}.bind(this))
.catch (function (err){
console.log(err);
return false;
});
} else {
return true;
}
};
return () => {CreateThem(counter, maxNum);};
}
Basically it creates orders in a recursive fashion, terminating after finding this.MaxRequests empty spots and then puts them together in a list under this.orders
Now I called this function by:
initialLoader.CreateNextBatch().then(function (success) {
console.log(success);
console.log("loaded");
initialLoader.initializeBatch();
});
However this fails:
TypeError: initialLoader.CreateNextBatch(...).then is not a function
at LoadExternDatabase...
Why isn't this working? What am I not understanding yet?
Edit: I've also tried to replace the return by a new promise:
return new Promise((resolve, reject) => {
CreateThem(counter, maxRequests);
resolve();
});
However this executes the resolve immediatelly, instead of waiting for CreateThem to complete. Nor directly the function by return CreateThem.bind(this, counter, maxRequests);
You should resolve a promise after the asynchronous operation done.
For example:
function test() {
return new Promise((resolve, reject) => {
setTimeout(() => {
// Resolved here!
// Because asynchronous function `setTimeout` ends here
resolve();
}, 1000);
})
}
In your code, if r >= 0, it will find an entry in database again until r less than 0, so it ends at else block:
if (r >= 0) {
// ...
} else {
// ends here
}
Maybe you could change your code to:
CreateNextBatch() {
return new Promise((resolve, reject) => {
this.orders.clear();
let maxNum = this.maxNum;
let counter = this.orderCounter;
let CreateThem = (counter, r) => {
if (r >= 0) {
//Order.find() finds an entry in a database
Order
.find({orderNr: counter.fullNumber()})
.then(function(orders) {
console.log("created order " + counter.fullNumber().toString());
let num = r;
if (orders.length === 0) {
this.OpenOrder(counter.fullNumber());
//adds order to this.orders
num -= 1;
}
counter.nextNumber();
return CreateThem(counter, num);
}.bind(this))
.catch (function (err){
console.log(err);
reject(err);
});
} else {
resolve(true);
}
};
});
// return () => {CreateThem(counter, maxNum);};
}
return new Promise((resolve, reject) => {
globalVarKeep = resolve;
globalVarBreak = reject;
});
Before that you would have had some code waiting for a promise or an event that says: -
CreateThem(counter, maxRequests);
globalVarKeep();
or
CreateThem(counter, maxRequests).then(globalVarKeep);
If that's appropriate.
The function initialLoader.CreateNextBatch() returns a function, not a promise, you should do: initialLoader.CreateNextBatch()()
The function CreateThem can return true if this.maxNum >= 0 and a promise of true or false depending on the recursion. But doesn't allways guaranteed return a promise. And () => {CreateThem(counter, maxNum);}; doesn't return anything either. You could try the following:
CreateNextBatch() {
this.orders.clear();
let maxNum = this.maxNum;
let counter = this.orderCounter;
let CreateThem = (counter, r) => {
if (r >= 0) {
//Order.find() finds an entry in a database
//you can return a promise here
return Order
.find({orderNr: counter.fullNumber()})
.then(function(orders) {
console.log("created order " + counter.fullNumber().toString());
let num = r;
if (orders.length === 0) {
this.OpenOrder(counter.fullNumber());
//adds order to this.orders
num -= 1;
}
counter.nextNumber();
return CreateThem(counter, num);
}.bind(this))
.catch (function (err){
console.log(err);
return false;
});
} else {
return Promise.resolve(true);
}
};
//you are not returning CreateThem here
return () => {return CreateThem(counter, maxNum);};
}
I am trying solve the following challenge where I have to write a function triggerActions that passes a callback into the processAction, and produces the output:
"Process Action 1"
"Process Action 2"
...
"Process Action n"
Here is the provided function:
function processAction(i, callback) {
setTimeout(function() {
callback("Processed Action " + i);
}, Math.random()*1000);
}
Function to code:
function triggerActions(count) {
}
Note that the code for processAction cannot be altered. I was thinking of using a Promise but I'm not sure how. I believe the setTimeout is actually synchronous so I don't know if async/await would work.
My attempt:
triggerActions = count => {
let promises = [];
for(let i=1; i<=count; i++) {
promises.push(new Promise( (resolve, reject) => processAction(i, str => resolve(str))));
}
let results = []
promises.forEach( promise => Promise.resolve(promise).then( async res => results.push(await res)));
return results;
}
I kind of like short and sweet:
var n = 5
var stop = 1
triggerActions = function(text) {
if (text) console.log(text)
if (stop <= n){
processAction(stop++, triggerActions)
}
}
triggerActions()
P.S
It occurred to me that perhaps you are only allowed to provide a function which means the stop variable declaration outside the function is a problem. It makes it a little more verbose, but you can wrap it all inside the function like this:
function triggerActions(stop) {
var rFn = (text) => {
if (text) console.log(text)
if (stop <= n){
processAction(stop++, rFn)
}
}
rFn()
}
triggerActions(1)
There you go:
// Your unaltered function
function processAction(i, callback) {
setTimeout(function() {
callback("Processed Action " + i);
}, Math.random()*1000);
}
// The function you want to implement
function triggerActions(count) {
var triggerAction = function (i) { // Local function to process the given action number:
if (i <= count) { // More actions to execute?
processAction(i, function (text) {// Process current action number and pass a callback in parameter
console.log(text); // Write the result of processAction
triggerAction(i + 1); // Trigger the next action
}); //
} //
}
triggerAction(1); // First things first: start at action one
}
// Call the function
triggerActions(10);
The original poster's instinct to use promises was correct.
The two solutions above may work but because each call to triggerActions() has to wait for the delay to elapse before the next call can be made, this is considerably slow.
Maybe this is what you want but here's an optimized solution using promises and Promise.all():
const processAction = (i, callback) => {
setTimeout(function() {
callback("Processed Action " + i);
}, Math.random()*1000);
}
const triggerActions = (n) => {
const promises = [];
const generatePromise = (i) => {
return new Promise((resolve, reject) => {
processAction(i, resolve);
});
}
for (let i = 1; i <= n; i += 1) {
promises.push(generatePromise(i));
}
Promise.all(promises)
.then((strings) => strings.forEach((string) => console.log(string)));
}
triggerActions(10);
To compare the performance differences, try running the two approaches side by side.
Here's my solution:
function processAction(i, callback) {
setTimeout(function() {
callback("Processed Action " + i);
}, Math.random()*1000);
}
// Function to code:
function triggerActions(count) {
const asyncArr = [];
for (let i = 1; i <= count; i++) {
asyncArr.push(new Promise(resolve => processAction(i, resolve)));
}
Promise.all(asyncArr).then((vals) => {
vals.forEach((val) => console.log(val))
});
}
triggerActions(5);
Here is my solution using Promise.all:
function triggerActions(count) {
const promises = range(count).map(
i => new Promise(resolve => processAction(i, resolve))
);
Promise.all(promises).then(results => {
results.forEach(result => console.log(result));
});
}
// Generates an array from 1...n
function range(n) {
return Array.from({ length: n }, (_, i) => i + 1);
}
The requirements are that the function ‘processAction’ should remain unchanged and invoked in a batch.
For this I have used the util.promisify function that takes a function and converts it into a promise. A promise can be invoked in a batch with Promise.all.
Another requirement is that the callback should output “Processed Action i” where i is a number. The anonymous function ‘func’ has been defined to do this.
The triggerActions function takes a number, x, creates an array of numbers containing indices from 0 to x and then invokes a count of x asynchronous functions simultaneously.
const {promisify} = require('util');
function processAction(i, callback) {
setTimeout(function() {
callback("Processed Action " + i);
}, Math.random()*1000);
}
const func = (param1) => console.log(param1);
const promisifyedProcessAction = promisify(processAction);
async function triggerActions(count) {
const arr = [];
for(let i = 0; i < count;)
arr.push(++i);
await Promise.all(
arr.map((value) => promisifyedProcessAction(value,func)));
}
triggerActions(5);
Here's an overview of all the possible approaches:
Callback-based:
Sequential:
function triggerActions(count) {
;(function recur(i = 0) {
processAction(i, (data) => {
console.log(data)
if (i < count) {
recur(i + 1)
}
})
})()
}
Concurrent
function triggerActions(count) {
const data = Array.from({ length: count })
for (let i = 0; i < count; i++) {
processAction(i, (result) => {
data[i] = result
count--
if (count == 0) {
for (const x of data) {
console.log(x)
}
}
})
}
}
Promise-based:
We can use this function to make processAction async:
function processActionP(i) {
return new Promise((res) => processAction(i, res))
}
Sequential:
async function triggerActions(count) {
for (let i = 0; i < count; i++) {
const data = await processActionP(i)
console.log(data)
}
}
Concurrent:
async function triggerActions(count) {
const data = await Promise.all(
Array.from({ length: count }, (_, i) => processActionP(i)),
)
for (const x of data) {
console.log(x)
}
}
Concurrent, using lodash/fp
const _ = require('lodash/fp')
const triggerActions = _.pipe(
_.range(0),
_.map(processActionP),
Promise.all.bind(Promise),
data => data.then(
_.each(console.log)
),
)