JavaScript: A better way to call multiple async functions in a row?

Question

I have 4 await calls that I need to call in a row. What I currently have works fine but it just looks like bad code to me. Is there a better way to write this? I tried using promise-chaining, but it just looked worse as expected.

adminSchema.statics.generateUsername = async(firstName, lastName) => {
    let generatedUsername = `${firstName}.${lastName}`.toLowerCase()

    let countTracker = 0

    const Count = ((count) => {
        if (count >= 1) {
            count++
            countTracker += count
            console.log("counted")
            console.log(countTracker)
        }
    })

    await Admin.countDocuments({ username: { $regex: new RegExp(generatedUsername) } }, (err, count) => {
        console.log("admin ran")
        Count(count)
    })
    await Teacher.countDocuments({ username: { $regex: new RegExp(generatedUsername) } }, (err, count) => {
        console.log("teacher ran")
        Count(count)
    })
    await Student.countDocuments({ username: { $regex: new RegExp(generatedUsername) } }, (err, count) => {
        console.log("student ran")
        Count(count)
    })
    await Scheduler.countDocuments({ username: { $regex: new RegExp(generatedUsername) } }, (err, count) => {
        console.log("scheduler ran")
        Count(count)
    })

    if (countTracker === 0) {
        generatedUsername = `${firstName}.${lastName}`.toLowerCase()
    } else {
        generatedUsername = `${firstName}.${lastName}.${countTracker}`.toLowerCase()
    }

    console.log(countTracker)
    return generatedUsername
}

Does countDocuments really return a Promise and accept a callback? — CertainPerformance
– CertainPerformance, Commented Aug 10, 2019 at 10:17
You could start with [Admin, Teacher, Student, Scheduler], map it to an array of Promises, then use Promise.all. No duplicate code that way. — user5734311
– user5734311, Commented Aug 10, 2019 at 10:24
Curious: Why do u have await if you are using callbacks? — ambianBeing
– ambianBeing, Commented Aug 10, 2019 at 10:25
@ambianBeing That code is pretty old and while I was still heavily learning new syntaxes and MEVN so I did some mistakes. Didn't honestly notice it until you called it out now, so thanks for that :P — Holiday
– Holiday, Commented Aug 10, 2019 at 10:30

Dacre Denny · Accepted Answer · 2019-08-10 10:41:38Z

One approach to run multiple async calls with minimal code would be via an async for-loop:

adminSchema.statics.generateUsername = async(firstName, lastName) => {
  let generatedUsername = `${firstName}.${lastName}`.toLowerCase()

  let countTracker = 0

  const Count = ((count) => {
    if (count >= 1) {
      count++
      countTracker += count
      console.log("counted")
      console.log(countTracker)
    }
  })

  /* Merge sequence of model counts into an asynchronous for-loop */
  for(const model of [Admin, Teacher, Student, Scheduler]) {

    /* 
    Evaluate async count() function per loop iteration. This will cause
    count() on each model to be called and completed sequentailly, one-
    after-the-next during iteration of the array. Note also that the
    callback is not needed */
    const count = await model.countDocuments({
      username: {
        $regex: new RegExp(generatedUsername)
      }
    });

    console.log(`${model.name} ran`);
    Count(count);
  }

  if (countTracker === 0) {
    generatedUsername = `${firstName}.${lastName}`.toLowerCase()
  } else {
    generatedUsername = `${firstName}.${lastName}.${countTracker}`.toLowerCase()
  }

  console.log(countTracker)
  return generatedUsername
}

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