Develop Reference

In a loop, innerHTML inserts only the last element called

I'm trying to display a countdown in several div tags with the same class.
But the problem is that only the last tag of the list contains the countdown.
Here is code:
const contentsDownDate = document.querySelectorAll(".countDown");
nbElement = contentsDownDate.length - 1;
for (var i = 0; i < nbElement; i++) {
var countDownDate = new Date("Jan 5, 2024 15:37:25").getTime();
// Update the count down every 1 second
x = setInterval(function() {
// Get today's date and time
var now = new Date().getTime();
// Find the distance between now and the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="demo"
contentsDownDate[i].innerHTML = days + "d " + hours + "h " +
minutes + "m " + seconds + "s ";
// If the count down is over, write some text
if (distance < 0) {
clearInterval(x);
contentsDownDate[i].innerHTML = "EXPIRED";
}
}, 1000);
}
I did the same thing by calling ids but still the same result, only the last id displays the countdown.
What can I do to solve this problem?
Note that the countdown code is taken from this: w3schools
PS: I also read that innerHTML prints at the end of the loop so it only prints the last tag and so you have to stop/pause the loop to print, especially with setInterval, but I already did it.
Unless this one was to update the countdown time? But in that case where should I place the other setInterval?

The reason why this is not working is because you enter the infinite loop in a blocking state, meaning that the interval is never entered as the browser is busy looping. Imagine the browser can only do one thing at a time, as in a single thread, so the loop is it, and cannot do anything else until it's done, and in your case it never.
Basically, if you put a setInterval() inside loop without clear it then the setInterval never stop and that mean the loop is infinite so it never complete.
Instead of that, put the loop inside the setInterval() will do the job. Let try this:
const contentsDownDate = document.querySelectorAll(".countDown");
nbElement = contentsDownDate.length-1;
var countDownDate = new Date("Jan 5, 2024 15:37:25").getTime();
// Update the count down every 1 second
x = setInterval(function() {
for (i=0; i<=nbElement; i++){
// Get today's date and time
var now = new Date().getTime();
// Find the distance between now and the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="demo"
contentsDownDate[i].innerHTML = days + "d " + hours + "h "
+ minutes + "m " + seconds + "s ";
// If the count down is over, write some text
if (distance < 0) {
clearInterval(x);
contentsDownDate[i].innerHTML = "EXPIRED";
}
}
}, 1000);

Set startdate to countdown

I have a countdown that ends at a specific time and date.
Is it possible to set a starting date for the countdown?
Start: June 14, 2018 15:00:00
End: June 17, 2018 23:59:59
// Set the date we're counting down to
var countDownDate = new Date("June 17, 2018 23:59:59").getTime();
// Update the count down every 1 second
var x = setInterval(function() {
// Get todays date and time
var now = new Date().getTime();
// Find the distance between now an the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="demo"
document.getElementById("countdown").innerHTML = "TEXT Countdown" + days + " days, " + hours + " h, "
+ minutes + " min & " + seconds + " sec";
// If the count down is over, write some text
if (distance < 0) {
clearInterval(x);
document.getElementById("countdown").innerHTML = "TEXT after countdown";
}
}, 1000);
<div id="countdown"></div>

Just delay the call to setInterval until the time you want. Your best bet, since timers get throttled on inactive tabs, is to check periodically and then kick things off when the time arrives:
var waitingTimer = setInterval(function() {
if (Date.now() < Date.parse("2018-06-14T15:00:00")) {
return;
}
clearInterval(waitingTimer);
// ...start the countdown
}, 1000);
You might want to express the time in UTC, since unfortunately the spec on what those strings mean without a timezone indicator changed (twice), whereas if you put the time in UTC and add a Z to the string, it's reliable.

How to display this code as D/HH/MM/SS?

This code basically puts out a countdown. The problem is, i would like it to be put out as D/HH/MM/SS as for example 1 day 05 hours 20 minutes 02 seconds, but i'm pretty new to coding, so i wonder if somebody could show/help me what is the right way to do it.
Thanks in advance!
Blockquote
<p id="demo"></p>
<script>
// Set the date we're counting down to
var countDownDate = new Date("Sep 5, 2018 15:37:25").getTime();
// Update the count down every 1 second
var x = setInterval(function() {
// Get todays date and time
var now = new Date().getTime();
// Find the distance between now an the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Display the result in the element with id="demo"
document.getElementById("demo").innerHTML = days + "d " + hours + "h "
+ minutes + "m " + seconds + "s ";
// If the count down is finished, write some text
if (distance < 0) {
clearInterval(x);
document.getElementById("demo").innerHTML = "EXPIRED";
}
}, 1000);
</script>

Sorry, I did not read your answer carefully enough the 1st time.
Details here about padStart
a new language feature and an old work around (repeated below).
function pad(num, size) {
//num, string to be padded with leading zeros
//size, size of result after padding
//pads up to 10 characters
var s = "000000000" + num;
return s.substr(s.length-size);
}
var test='1';
console.log(pad('123456789',10)); //pads up to 10 char, result '0123456789'
console.log(pad(test,2)); //pads up to 2 char, result '01'

Set Countdown timer then display voting open then after voting period display voting ends

Here are my code on my current program. I have a running code for countdown timer my problem now is when the VOTING PERIOD ENDS I want to display Voting Ends instead of it always displaying voting open.
<script>
// Set the date we're counting down to
var countDownDate = new Date("<?php echo $countdown['datestart']; ?>").getTime();
var endDate = new date("<?php echo $countdown['dateend']; ?>").getTime();
// Update the count down every 1 second
var x = setInterval(function() {
// Get todays date and time
var now = new Date().getTime();
// Find the distance between now an the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="demo"
document.getElementById("demo").innerHTML = days + "d " + hours + "h "
+ minutes + "m " + seconds + "s ";
// If the count down is over, write some text
if (distance < 0) {
clearInterval(x);
document.getElementById("demo").innerHTML = "Voting now Opens";
}
// If date end is over display some text
//display voting period ends
}, 1000);
</script>

At a glance, i can see that your "endDate" line has an error:
var endDate = new date(.....
it should be Date with a capital 'D' as is for the var countDownDate i.e.
var endDate = new Date(.....
Assuming the rest of the code is correct (and it seems ok) - should be fine.
If that doesn't solve it - from your question it is easy to decipher that the if the following function always resolves to false and hence will never fire enclosed code which clears the 'x' interval and shows that voting is open.
if (distance < 0) {...}
If what I would do is console.log(countDownDate);, console.log(now); and why not also console.log(distance); ideally immidiately after the declaration:
// Find the distance between now an the count down date
var distance = countDownDate - now;
if you are unsure how to use the console.log() function please refer to the following link: https://developers.google.com/web/tools/chrome-devtools/console/

To add the end voting message, you will need to continue the interval until the voting has ended. To make things a little simpler, we have split the code into 3 sections using if...else if...else. In each of these, we handle the respective display for that scenario. It has the added benefit of not doing calculations when it is not needed.
If distance > 0, the voting has not started.
If endDate > now, the voting hasn't ended. I am assuming that the PHP output will result in an accurate date for this scenario. Read more.
Any other scenario means voting has ended.
<script>
// Set the date we're counting down to
var countDownDate = new Date("<?php echo $countdown['datestart']; ?>").getTime();
var endDate = new Date("<?php echo $countdown['dateend']; ?>").getTime();
// Update the count down every 1 second
var x = setInterval(function() {
// Get todays date and time
var now = new Date().getTime();
// Find the distance between now an the count down date
var distance = countDownDate - now;
if (distance > 0) {
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="demo"
document.getElementById("demo").innerHTML = days + "d " + hours + "h "
+ minutes + "m " + seconds + "s ";
}
else if (endDate > now) {
// If the count down is over, write some text
document.getElementById("demo").innerHTML = "Voting now Opens";
}
else {
// If date end is over display some text
//display voting period ends
document.getElementById("demo").innerHTML = "Voting Ended";
clearInterval(x);
}
}, 1000);
</script>

timer data start for next week

function countDown(){
// Set the date we're counting down to
var countDownDate = new Date("july 11, 2017 10:19:00").getTime();
// Update the count down every 1 second
var x = setInterval(function() {
// Get todays date and time
var now = new Date().getTime();
// Find the distance between now an the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
// Output the result in an element with id="demo"
document.getElementById("demo").innerHTML = days + "d " + hours + "h "
+ minutes + "m " + seconds + "s ";
// If the count down is over, write some text
if (distance < 0) {
countDownDate = new Date("july 18, 2017 10:19:00").getTime();
}
}, 1000);
}
countDown();
what I want to reach is the every week the timer will start count to the next week.
I have something that start every week in the same day and in the same hour.
I don't want to rewrite the code every week :/
Thank you.

so why so much calculation is needed just to calculate how many seconds are remaining to start of next week? for example I am writing a sample code to calculate it.
function distranceToNextWeekStartInSeconds() {
var now = new Date()
var dayDiff = 7 - now.getDay();
var startOfNextWeek = new Date(now.valueOf());
startOfNextWeek.setDate(now.getDate() + dayDiff);
startOfNextWeek.setHours(0);
startOfNextWeek.setMinutes(0);
startOfNextWeek.setSeconds(0);
return Math.floor((startOfNextWeek - now) / 1000);
}
console.log('Seconds remaining to next week start: ' + distranceToNextWeekStartInSeconds())
and you can simply call this function inside your timer for a live calculation and display purpose, That's It.

I assumed you wanted to count down to every next tuesday at 10:19:00.
I'm too lazy right now to test every cases, ut I think it should work.
function getNextTuesday() {
// Get the date from now
var date = new Date();
// Set target hour/minute/seconds
date.setHours(10);
date.setMinutes(19);
date.setSeconds(0);
// Seek for the next tuesday
var actualDay = date.getDay();
var targetDay = 2; //Tuesday
// diff will give us the day span between today and the next tuesday
var diff = targetDay - actualDay;
// If the diff is less than 0 (we're sunday or monday, or we fall on the exact day, minutes after the target hour) then add a week
if (diff < 0 || (date.getTime() - new Date().getTime()) <= 0) {
diff += 7;
}
// Finally add the day span to the current date
date.setDate(date.getDate() + diff);
return date;
}
function countDown() {
// Set the date we're counting down to
var countDownDate = getNextTuesday();
// Update the count down every 1 second
var x = setInterval(function() {
// Get todays date and time
var now = new Date().getTime();
// Find the distance between now an the count down date
var distance = countDownDate - now;
// Time calculations for days, hours, minutes and seconds
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
if (distance < 0) {
// If the count down is over, write some text
document.getElementById("demo").innerHTML = 'IT\'S HAPPENING !';
countDownDate = getNextTuesday();
} else {
// Output the result in an element with id="demo"
document.getElementById("demo").innerHTML = days + "d " + hours + "h " + minutes + "m " + seconds + "s ";
}
}, 1000);
}
countDown();
<div id="demo"></div>