While loops using Await Async.

loops asynchronous while-loop async-await ecmascript-next
Hcharlanes picture Hcharlanes · Aug 23, 2016 · Viewed 27.9k times · Source

This Javascript function seems to use the while loop in an asynchronous way. Is it the correct way to use while loops with asynchronous conditions?

 var Boo;
 var Foo = await getBar(i)
 while(Foo) {
    Boo = await getBar3(i)
    if (Boo) {
      // something
    }
    Foo = await getBar(i)
    i++
  }

What I think it does is this:

var Boo;
var Foo;
getBar(i).then( (a) => {
  Foo = a;
  if(Foo) {
    getBar3(i).then( (a) => {
      Boo = a
      if(Boo) {
        //something
        i++;
        getBar(i).then( (a} => { Repeat itself...} 
      }
   }
  }
})

If that's totally false could you show another way to do it with async await + while loop?

Thanks!!

Answer

Bergi picture Bergi · Aug 23, 2016

Is it the correct way to use while loops with asynchronous conditions?

Yes. async functions simply suspend their execution on every await until the respective promises fulfills, and any control structures continue to work as before.

Related questions

Node.js - Using the async lib - async.foreach with object

I am using the node async lib - https://github.com/caolan/async#forEach and would like to iterate through an object and print out its index key. Once complete I would like execute a callback. Here is what I …

Read More
For-each over an array in JavaScript

How can I loop through all the entries in an array using JavaScript? I thought it was something like this: forEach(instance in theArray) Where theArray is my array, but this seems to be incorrect.

Read More
Loop through an array in JavaScript

In Java you can use a for loop to traverse objects in an array as follows: String[] myStringArray = {"Hello", "World"}; for (String s : myStringArray) { // Do something } Can you do the same in JavaScript?

Read More