Executing promises in a for-loop within a setTimeout function

Question

Executing promises in a for-loop within a setTimeout function

Looking to integrate a web API with JavaScript/AngularJS 1.x on a timed interval due to rate limiting. The code provided attempts to achieve this by utilizing a list of objects called RecordList and a function called setDelay that introduces delays with the setTimeout method.

The issue arises when attempting to determine if all promises within the setTimeout function have been successfully resolved. Traditional methods such as Promise.all and $q.all don't work seamlessly in conjunction with setTimeout. Any suggestions for an alternative approach?

var waitInterval = 300;
var promiseArray = [];

function setDelay(obj, s) {
  setTimeout(function() {
    var SomePromise = $http.post('odataURI', obj).then(function success(result) {
      //resolve(result);
    });
    promiseArray.push(SomePromise);
  }, waitInterval * s);
}
for (var s = 1; s <= RecordList.length; s++) {
  setDelay(RecordList[s - 1], s);
}

javascript angularjs http promise settimeout

Answer 1

Answer №1

If you want to run the next promise after one has finished, consider using a recursive function.

function postData(num) {
  return Promise.resolve(num);
}

function addDelay(num, milliseconds) {
  return new Promise(function(resolve, reject) {
    setTimeout(function() {
       postData(num).then(function(response) {
        resolve(response);
      });
    }, milliseconds)
  })
}

function iterateList(list, delay = 1000, index = 0, results = []) {
  addDelay(list[index], delay).then(
    function(response) {
      console.log(response);
      results.push(response);
      if (index == list.length - 1) {
        console.log('Results: ', results); // Additional logic can be added here
        return results;
      } else {
        return iterateList(list, delay, index + 1, results);
      }
    }
  ); 
}

var dataList = [1, 2, 3, 4, 5];
iterateList(dataList);

Answer 2

If you want to run the next promise after one has finished, consider using a recursive function.

function postData(num) {
  return Promise.resolve(num);
}

function addDelay(num, milliseconds) {
  return new Promise(function(resolve, reject) {
    setTimeout(function() {
       postData(num).then(function(response) {
        resolve(response);
      });
    }, milliseconds)
  })
}

function iterateList(list, delay = 1000, index = 0, results = []) {
  addDelay(list[index], delay).then(
    function(response) {
      console.log(response);
      results.push(response);
      if (index == list.length - 1) {
        console.log('Results: ', results); // Additional logic can be added here
        return results;
      } else {
        return iterateList(list, delay, index + 1, results);
      }
    }
  ); 
}

var dataList = [1, 2, 3, 4, 5];
iterateList(dataList);

Answer 3

Answer №2

If you want to achieve the same result, consider using `async` and `await` in your code.

const waitInterval = 300;
const promiseArray = [];

async function LoopFunction() {
  let dataMain;
  for (let s = 1; s <= RecordList.length; s++) {
     dataMain = await setDelay(RecordList[s - 1], s); // You will receive the data after consuming the API successfully.
  }
}

function setDelay(obj, s) {
 return new Promise((resolve, reject) => {
   setTimeout(() => {
     const SomePromise = $http.post('odataURI', obj).then(result => {
       resolve(result);
     });
    }, waitInterval * s);
 }); 
}

I hope this solution is beneficial for you.

Answer 4

If you want to achieve the same result, consider using `async` and `await` in your code.

const waitInterval = 300;
const promiseArray = [];

async function LoopFunction() {
  let dataMain;
  for (let s = 1; s <= RecordList.length; s++) {
     dataMain = await setDelay(RecordList[s - 1], s); // You will receive the data after consuming the API successfully.
  }
}

function setDelay(obj, s) {
 return new Promise((resolve, reject) => {
   setTimeout(() => {
     const SomePromise = $http.post('odataURI', obj).then(result => {
       resolve(result);
     });
    }, waitInterval * s);
 }); 
}

I hope this solution is beneficial for you.

Answer 5

Answer №3

Even without using recursion, it is still possible to achieve the desired outcome.

var interval = 300;
var promises = [];
var tickCount = 0;

function setDelay(obj, s) {
  setTimeout(function() {
    var somePromise = Promise.resolve(obj);
    somePromise.then(function success(result) {
      tickCount++;
      console.log(result);
      if (tickCount === RecordList.length) {
          Promise.all(promises).then((res) => {
            console.log(res);
          });
      }
    });
    promises.push(somePromise);
  }, interval * s);
}

var RecordList = [1,2,3,4,5];

for (var s = 1; s <= RecordList.length; s++) {
  setDelay(RecordList[s - 1], s);
}

Answer 6

Even without using recursion, it is still possible to achieve the desired outcome.

var interval = 300;
var promises = [];
var tickCount = 0;

function setDelay(obj, s) {
  setTimeout(function() {
    var somePromise = Promise.resolve(obj);
    somePromise.then(function success(result) {
      tickCount++;
      console.log(result);
      if (tickCount === RecordList.length) {
          Promise.all(promises).then((res) => {
            console.log(res);
          });
      }
    });
    promises.push(somePromise);
  }, interval * s);
}

var RecordList = [1,2,3,4,5];

for (var s = 1; s <= RecordList.length; s++) {
  setDelay(RecordList[s - 1], s);
}

Executing promises in a for-loop within a setTimeout function

Answer №1

Answer №2

Answer №3

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