Execute function when condition is met

February 3, 2022

i have a probably stupid question, but i cant figure it out.

In a piece of code below I have a global variable guestsTotal and event hadler where this variable is incremented by 1 by clicking button.

I’m trying to display in console some message when guestsTotal will be 12. But this doesn’t work.
My friend said that this wouldn’t work because event hadlers are asynchronous in JS. And my script was already executed.

So is there a way to do some actions when the value of guestsTotal will be 12?

let adultTotal = 0
let childTotal = 0
let babyTotal = 0
let guestsTotal = 0

adultButtonPlus.addEventListener('click', function (evt) {
    adultTotal++
    guestsTotal++
    adultCounter.textContent = adultTotal
    guestsInput.value = `${guestsTotal} guests`
})

if (guestsTotal === 12) {
    console.log('message')
}

>Solution :

You can do it two ways:

Check for the condition inside your event handler. This is very simple to do:

let adultTotal = 0
let childTotal = 0
let babyTotal = 0
let guestsTotal = 0
let adultButtonPlus = document.querySelector('#aButton');
adultButtonPlus.addEventListener('click', function (evt) {
    adultTotal++
    guestsTotal++
    //adultCounter.textContent = adultTotal
    //guestsInput.value = `${guestsTotal} guests`
if (guestsTotal === 12) {
    console.log('message')
}
});

<button id="aButton">Adult</button>

Or make use of getters and setters to listen to value changes in your guestsTotal count.

let adultTotal = 0
let childTotal = 0
let babyTotal = 0
const guestsTotal = {
  count: 0,
  get total() {
   return this.count;
  },
  set total(newCount) {
    this.count = newCount;
    if(this.count === 3){
      console.log('count is 3');
    }
    else if(this.count === 12){
      console.log('count is 12');
    }
  }
};


let adultButtonPlus = document.querySelector('#aButton');
adultButtonPlus.addEventListener('click', function (evt) {
    adultTotal++
    guestsTotal.total = guestsTotal.total+1;
    //adultCounter.textContent = adultTotal
    //guestsInput.value = `${guestsTotal} guests`
if (guestsTotal === 12) {
    console.log('message')
}
});