Call one function after another function having a async function in itself

Question

How to call one function a() after another function b() when b() contains a async function c()?

A() {

}

B() {

    //do sometihng
    c(); //async function 
    //do something

}

I want to call A() if B() including c() is done executing. But I can not modify function B().

Jonas Wilms · Answer 1 · 2017-07-31T16:35:11.800

3

async function b(){
  await c();
}

function a(){}

(async function(){
  await b();
  a();
})()

make b await c, then you can await b and execute a. another way would be:

function b(){

  return c();
}

b().then(a);

edited Jul 31 '17 at 16:35

answered Jul 31 '17 at 16:32

Jonas Wilms

note that `async` and `await` not supported in all browsers – charlietfl Jul 31 '17 at 16:33
no, not at all... lots of legacy browsers that don't support them – charlietfl Jul 31 '17 at 16:35
@charlieftl no , i based my use of *async* on the question, where the op is talking about *async functions* ... – Jonas Wilms Jul 31 '17 at 16:35
but I can not modify anything inside b()...Its already defined. – Avinash Jul 31 '17 at 16:37
@avinash then its impossible – Jonas Wilms Jul 31 '17 at 16:38
@Avinash, then `b` is badly designed, and you are without hope. – trincot Jul 31 '17 at 16:38
@trincot what about with({b:_=>b().then(a)}){c)} ? !) – Jonas Wilms Jul 31 '17 at 16:40
@Jonas, an object with a `b` property? I don't see (besides the syntax errors) where you want to go to with that. – trincot Jul 31 '17 at 16:48
@trincot yep, that is used for variable lookup... oh and theres just a ( missing :/ – Jonas Wilms Jul 31 '17 at 16:49

score 1 · Answer 2 · answered Jul 31 '17 at 16:36

the keyword awaitis what you're looking for.

From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/await : If a Promise is passed to an await expression, it waits for the Promise's resolution and returns the resolved value.

async function c() {
   await b();
   a();
}

2 Answers2