How do I use async/await in JavaScript?

Question

I have the following code:

function one() {

    setTimeout(() => {

        console.log('one');
    }, 2000);
}

function two() {
    console.log('two');
}

function three() {
    console.log('three');
}

function wrapper() {
    one();
    two();
    three();
}

wrapper();

This of course console logs them in the following order: two three one

Using async / await I'd like to console log them in the following order: one two three

I'm not sure how to achieve this.

Thanks

Answer 1

You have to make use of async and Promises. Please have a look at the documentation.

The code below returns a Promise call. The Promise itself sets a timeout of two seconds and after this time it logs "one" to the console.

You can wait for the promise to finish using the await-keyword right before the function call.

Note that the functions have to be async.

 return new Promise((resolve)=>{
    setTimeout(() => {
        console.log('one');
        resolve();
      }, 2000);
  })

---

Heres a updated version of your code - I hope this helps:

async function one() {
  return new Promise((resolve)=>{
    setTimeout(() => {
        console.log('one');
        resolve();
      }, 2000);
  })
}

async function two() {
  console.log('two');
}

async function three() {
  console.log('three');
}

async function wrapper() {
  await one();
  await two();
  await three();
}

wrapper();

Answer 2

async function one(){ 
  await new Promise(resolve => 
  setTimeout(async () => {
     await resolve(console.log('one'));
    }, 2000));
 
}

function two() {
    console.log('two');
}

function three() {
    console.log('three');
}
async function wrapper(){ await one(); two(); three();}

wrapper();