synchronous execution of function after multiple asynchronous functions

Question

I have 3 asynchronous typescript methods, which are to be executed in parallel as i have shown below. I want to execute the last function after all the 3 of them had finished the execution . How could i accompany this.

this.getTimeLecs(prevTimeStartStr , nowTimeStartStr).then((result) => {
  // console.log(result);
  this.previousData = result;
});
this.getTimeLecs(nowTimeStartStr, nextTimeStartStr).then((result) =>{
  this.currentData = result;
});
this.getTimeLecs(nextTimeStartStr , nextTimeEnd ),then(result) => {
  this.nextData = result;
};
finalFunction();

Manu Nair · Accepted Answer · 2018-10-28 15:25:54Z

2

With async/await this can be achieved.

export class AsyncAwaitExample {
  constructor() {
  }
  getTimeLecs(str1, str2) {
    return Promise.resolve(str1 + ":" + str2).then(v => console.log(v));
  }
  async getTimeALL() {
    await Promise.all([
      this.getTimeLecs(10, 20),
      this.getTimeLecs(20, 30),
      this.getTimeLecs(30, 40)]
    );
    this.finalCall();
  }
  finalCall() {
    console.log('final call');
  }
}

let example = new AsyncAwaitExample();
example.getTimeALL();

Here

 await Promise.all([
          this.getTimeLecs(10, 20),
          this.getTimeLecs(20, 30),
          this.getTimeLecs(30, 40)]
        );

waits for all the promises to get resolved and then calls finalCall() method. to check whether this works or not, remove await from the above code and see the results in console. Check the Demo, to see it in action.

answered Oct 28, 2018 at 15:25

Manu Nair

702 silver badges4 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

dinith jayabodhi Over a year ago

Thanks....someone please give due credit to him by up voting the answer

Patrick Sturm · Accepted Answer · 2018-10-28 06:03:27Z

0

I have encountered this situation a few times and a very simple method is to use a counter at the top of the scope. Then at each callback, increment the counter and if it is equal to the total amount of calls, the function is ready to be called.

However, there exists far more glamorous methods such as the async library, which is much better because you can add more functions without re-evaluating the counter and changing each test.

answered Oct 28, 2018 at 6:03

Patrick Sturm

312 bronze badges

1 Comment

dinith jayabodhi Over a year ago

thanks for the solution...but i would prefer solution from async library

Collectives™ on Stack Overflow

synchronous execution of function after multiple asynchronous functions

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related