Circular countdown JavaScript from 10 to Zero

Question

I have been trying to reverse the countdown in this demo from 10 down to zero Without luck.

I have tried reversing the countdown by doing this:

(1*(initialOffset/time))-initialOffset )

It did reverse the animated circle but not the countdown.

Any ideas?

Thanks

var time = 10;
var initialOffset = '440';
var i = 1

/* Need initial run as interval hasn't yet occured... */
$('.circle_animation').css('stroke-dashoffset', initialOffset-(1*(initialOffset/time)));

var interval = setInterval(function() {
    $('h2').text(i);
    if (i == time) {  	
        clearInterval(interval);
        return;
    }
    $('.circle_animation').css('stroke-dashoffset', initialOffset-((i+1)*(initialOffset/time)));
    i++;  
}, 1000);

.item {
    position: relative;
    float: left;
}

.item h2 {
    text-align:center;
    position: absolute;
    line-height: 125px;
    width: 100%;
}

svg {
    transform: rotate(-90deg);
}

.circle_animation {
    stroke-dasharray: 440; /* this value is the pixel circumference of the circle */
    stroke-dashoffset: 440;
    transition: all 1s linear;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="item">
    <h2>0</h2>
    <svg width="160" height="160" xmlns="http://www.w3.org/2000/svg">
        <circle id="circle" class="circle_animation" r="69.85699" cy="81" cx="81" stroke-width="8" stroke="#6fdb6f" fill="none"/>
    </svg>
</div>

Here is also a codepen copy:

https://codepen.io/kaolay/pen/LRVxKd

Answer 1

Try $('h2').text(time - i); instead of $('h2').text(i);

I also added $('h2').text(time); as the 4th line to draw 10 at the beginning

Also, the first part of the circle is not animated in your code, so I changed this line:

$('.circle_animation').css('stroke-dashoffset', initialOffset-(1*(initialOffset/time)));

To this block:

$('.circle_animation').css('stroke-dashoffset', initialOffset);
setTimeout(() => {
    $('.circle_animation').css('stroke-dashoffset', initialOffset-(1*(initialOffset/time)));
})

var time = 10;
var initialOffset = '440';
var i = 1;
$('h2').text(time); // adding 10 at the beginning if needed

/* Need initial run as interval hasn't yet occured... */
$('.circle_animation').css('stroke-dashoffset', initialOffset);
setTimeout(() => {
    $('.circle_animation').css('stroke-dashoffset', initialOffset-(1*(initialOffset/time)));
})


var interval = setInterval(function() {
    $('h2').text(time - i); // here is the clue
    if (i == time) {  	
        clearInterval(interval);
        return;
    }
    $('.circle_animation').css('stroke-dashoffset', initialOffset-((i+1)*(initialOffset/time)));
    i++;  
}, 1000);

.item {
    position: relative;
    float: left;
}

.item h2 {
    text-align:center;
    position: absolute;
    line-height: 125px;
    width: 100%;
}

svg {
    transform: rotate(-90deg);
}

.circle_animation {
    stroke-dasharray: 440; /* this value is the pixel circumference of the circle */
    stroke-dashoffset: 440;
    transition: all 1s linear;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="item">
    <h2>0</h2>
    <svg width="160" height="160" xmlns="http://www.w3.org/2000/svg">
        <circle id="circle" class="circle_animation" r="69.85699" cy="81" cx="81" stroke-width="8" stroke="#6fdb6f" fill="none"/>
    </svg>
</div>

Answer 2

If you update this line $('h2').text(time - i); then you'll get the numeric countdown. I also initalize i = 0 so that the starting number is 10:

var time = 10;
var initialOffset = '440';
var i = 0

/* Need initial run as interval hasn't yet occured... */
$('.circle_animation').css('stroke-dashoffset', initialOffset-(1*(initialOffset/time)));

var interval = setInterval(function() {
		$('h2').text(time - i);
		if (i == time) {  	
      clearInterval(interval);
			return;
    }
    $('.circle_animation').css('stroke-dashoffset', initialOffset-((i+1)*(initialOffset/time)));
    i++;  
}, 1000);

.item {
    position: relative;
    float: left;
}

.item h2 {
    text-align:center;
    position: absolute;
    line-height: 125px;
    width: 100%;
}

svg {
    transform: rotate(-90deg);
}

.circle_animation {
  stroke-dasharray: 440; /* this value is the pixel circumference of the circle */
  stroke-dashoffset: 440;
  transition: all 1s linear;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="item">
    <h2>0</h2>
    <svg width="160" height="160" xmlns="http://www.w3.org/2000/svg">
      <circle id="circle" class="circle_animation" r="69.85699" cy="81" cx="81" stroke-width="8" stroke="#6fdb6f" fill="none"/>
    </svg>
</div>