Using Async/Await on multiple settimeout

Question

To understand async/await, I am trying to display a console message once settimeout runs and expires. How do I fix my code below? I have 5 settimeout function and each should display respective message once finished.

function t1(){
    setTimeout(() => {
    console.log("1")
    }, 1000);
}

function t2(){
    setTimeout(() => {
    console.log("2")
    }, 2000);
}

function t3(){
    setTimeout(() => {
    console.log("3")
    }, 3000);
}

function t4(){
    setTimeout(() => {
    console.log("4")
    }, 4000);
}

function t5(){
    setTimeout(() => {
    console.log("5")
    }, 5000);
}

async function main(){
    await t1();
    console.log("1sec done");
    await t2();
    console.log("2sec done");
    await t3();
    console.log("3sec done");
    await t4();
    console.log("4sec done");
    await t5();
    console.log("Yay! I am all done");
}
main();

Answer 1

You should use Promises

function t1(){
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        console.log("1");
        resolve();
      }, 1000);
   });
}

function t2(){
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        console.log("2");
        resolve();
      }, 1000);
   });
}

function t3(){
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        console.log("3");
        resolve();
      }, 1000);
   });
}

function t4(){
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        console.log("4");
        resolve();
      }, 1000);
   });
}

function t5(){
    return new Promise(function(resolve, reject) {
      setTimeout(() => {
        console.log("5");
        resolve();
      }, 1000);
   });
}

async function main(){
    await t1();
    console.log("1sec done");
    await t2();
    console.log("2sec done");
    await t3();
    console.log("3sec done");
    await t4();
    console.log("4sec done");
    await t5();
    console.log("Yay! I am all done");
}
main();

Answer 2

You are doing two mistakes

• First you are using await before a calling a function t1,t2,t3.... await should be used on Promises.
• You are passing 1000,2000,... to setTimeout(). You should create a function which returns a Promise which will be resolved after 1 second
• Use await before the promise returned by that function

let afterOne = (num) => new Promise(res => {
    setTimeout(()=>{
      //log the number passed to function after 1000 ms
      console.log(num);
      //resolve the current promise so then next setTimeout could be set
      res();
   },1000)
  })
async function main(){
    /*This loop does same as
       await afterOne(0);
       await afterOne(1);
       await afterOne(2)
       await afterOne(3);
       await afterOne(4);
    */
    for(let i = 0;i<5;i++){
      await afterOne(i)
    }
}
main();