javascript - Check if interval exists, if so, clear the interval and start a new one - Stack Overflow

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I'm working on a countdown date script. However, the environment I'm working in does not refresh the page on submission, so I'm having an issue with multiple intervals being created. I believe if there was a way to check if there is an interval running, then to clear it and create a new one. But I'm not sure of how to do this. Of course, if there is a better strategy than how I currently have my code set up, then feel free to provide that as well.

My Code:

//get ready for a-togglin'
var finishedMessage = document.getElementById('finshedMessage');
//get dates value
var dateValue = document.getElementById('dateInput').innerText;

var dateEntered = new Date(dateValue);

//set the date we're counting down too
var targetDate = new Date(dateEntered).getTime();

//Update the countdown every second
var countInterval = setInterval(function() {
  var now = new Date().getTime();

  //get time remaining from now
  var timeRemaining = targetDate - now;

  //time calculations : days, hours, minutes and seconds
  var days = Math.floor(timeRemaining / (1000 * 60 * 60 * 24));
  var hours = Math.floor((timeRemaining % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((timeRemaining % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((timeRemaining % (1000 * 60)) / 1000);

  //When the countdown is finished, report back pletion text
  if (timeRemaining <= 0 || NaN) {
    finishedMessage.style.display = "inline-block";
    clearInterval(countInterval);
  } else {
    //if day is over a year count the years remaining if no years just count       days
    if (days > 365) {
      var years = Math.floor(days / 365);
      days = days % 365;
      document.getElementById("report").innerHTML = years + "Y " + days + "D " + hours + "H " + minutes + "M " + seconds + "s ";
    } else {
      //report the remaining time to report div
      document.getElementById("report").innerHTML = days + "D " + hours + "H " + minutes + "M " + seconds + "s ";
    }
  }
}, 1000);

I'm working on a countdown date script. However, the environment I'm working in does not refresh the page on submission, so I'm having an issue with multiple intervals being created. I believe if there was a way to check if there is an interval running, then to clear it and create a new one. But I'm not sure of how to do this. Of course, if there is a better strategy than how I currently have my code set up, then feel free to provide that as well.

My Code:

//get ready for a-togglin'
var finishedMessage = document.getElementById('finshedMessage');
//get dates value
var dateValue = document.getElementById('dateInput').innerText;

var dateEntered = new Date(dateValue);

//set the date we're counting down too
var targetDate = new Date(dateEntered).getTime();

//Update the countdown every second
var countInterval = setInterval(function() {
  var now = new Date().getTime();

  //get time remaining from now
  var timeRemaining = targetDate - now;

  //time calculations : days, hours, minutes and seconds
  var days = Math.floor(timeRemaining / (1000 * 60 * 60 * 24));
  var hours = Math.floor((timeRemaining % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((timeRemaining % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((timeRemaining % (1000 * 60)) / 1000);

  //When the countdown is finished, report back pletion text
  if (timeRemaining <= 0 || NaN) {
    finishedMessage.style.display = "inline-block";
    clearInterval(countInterval);
  } else {
    //if day is over a year count the years remaining if no years just count       days
    if (days > 365) {
      var years = Math.floor(days / 365);
      days = days % 365;
      document.getElementById("report").innerHTML = years + "Y " + days + "D " + hours + "H " + minutes + "M " + seconds + "s ";
    } else {
      //report the remaining time to report div
      document.getElementById("report").innerHTML = days + "D " + hours + "H " + minutes + "M " + seconds + "s ";
    }
  }
}, 1000);

• javascript
• intervals

Share Improve this question Follow edited Sep 19, 2018 at 16:06 Andrew L 5,49611 gold badge2828 silver badges3939 bronze badges asked Sep 19, 2018 at 16:02 Cody CarmichaelCody Carmichael 18733 silver badges1616 bronze badges 1

• if (countInterval) clearInterval(countInterval) – epascarello Commented Sep 19, 2018 at 16:05

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3 Answers 3

Sorted by: Reset to default 4

I'm afraid there's not how to clear all intervals declared without having the value returned from them. But you can save the reference to the global window object when running it for the first time, so you can reset it whenever you want:

if (window.countInterval) clearInterval(window.countInterval)
window.countInterval = setInterval(function () {
  /* your code here */
})

It is not an error to call clearInterval for interval id already stopped. So you can do just

clearInterval(intervalId);
intervalId = setInterval(.....);

The way I keep track of the interval ID's is to push them into an array.

//This is to keep track of intervals and timeouts
if( typeof ID == "undefined" )
{ var ID = []; }
// make sure no intervals are running
ClearAll();
// start your interval like this
ID.push(
    setInterval( function(){  }, 200  )
);
// function to clear all running intervals in the array
function ClearAll(){
    for(let i = 0; i < ID.length; i++){
        clearInterval(  ID[ i ]  );
    }
}

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