Count animation from number A to B

I am updating a numeric value inside an element by doing intervalled ajax requests.

To make the whole thing a bit more alive, I want to count from the current value to the new one, by partially in- or decreasing the value over a time of n sec.

So basically something like this:

<div id="value">100</div>
<script type="text/javascript">
    /** Decrease $value (over a time of 2 seconds) till it reaches 25 */
    $value.increaseAnimation(-75, {duration:2});
</script>

Is there a javascript library for doing so?

Answers:

Answer

You can just code it yourself pretty simply:

function animateValue(id, start, end, duration) {
    var range = end - start;
    var current = start;
    var increment = end > start? 1 : -1;
    var stepTime = Math.abs(Math.floor(duration / range));
    var obj = document.getElementById(id);
    var timer = setInterval(function() {
        current += increment;
        obj.innerHTML = current;
        if (current == end) {
            clearInterval(timer);
        }
    }, stepTime);
}

animateValue("value", 100, 25, 5000);
#value {
    font-size: 50px;
}
<div id="value">100</div>


Here's is a more accurate version that self adjusts in case the timer intervals aren't perfectly accurate (which they sometimes aren't):

function animateValue(id, start, end, duration) {
    // assumes integer values for start and end
    
    var obj = document.getElementById(id);
    var range = end - start;
    // no timer shorter than 50ms (not really visible any way)
    var minTimer = 50;
    // calc step time to show all interediate values
    var stepTime = Math.abs(Math.floor(duration / range));
    
    // never go below minTimer
    stepTime = Math.max(stepTime, minTimer);
    
    // get current time and calculate desired end time
    var startTime = new Date().getTime();
    var endTime = startTime + duration;
    var timer;
  
    function run() {
        var now = new Date().getTime();
        var remaining = Math.max((endTime - now) / duration, 0);
        var value = Math.round(end - (remaining * range));
        obj.innerHTML = value;
        if (value == end) {
            clearInterval(timer);
        }
    }
    
    timer = setInterval(run, stepTime);
    run();
}

animateValue("value", 100, 25, 5000);
#value {
    font-size: 50px;
}
<div id="value">100</div>

Answer

I had a slightly different approach to this kind of animation. Based on these assumptions:

  1. there is a starting text (as fallback for non-JS browser or google indexing)
  2. this text can contains non-numeric chars
  3. the function take an element directly as first param (as opposed to an element Id)

So, if you want to animate a simple text like "+300% gross margin", only the numeric part will be animated.

Moreover, all params have now a default value for start, end and duration.

https://codepen.io/lucamurante/pen/gZVymW

function animateValue(obj, start = 0, end = null, duration = 3000) {
    if (obj) {

        // save starting text for later (and as a fallback text if JS not running and/or google)
        var textStarting = obj.innerHTML;

        // remove non-numeric from starting text if not specified
        end = end || parseInt(textStarting.replace(/\D/g, ""));

        var range = end - start;

        // no timer shorter than 50ms (not really visible any way)
        var minTimer = 50;

        // calc step time to show all interediate values
        var stepTime = Math.abs(Math.floor(duration / range));

        // never go below minTimer
        stepTime = Math.max(stepTime, minTimer);

        // get current time and calculate desired end time
        var startTime = new Date().getTime();
        var endTime = startTime + duration;
        var timer;

        function run() {
            var now = new Date().getTime();
            var remaining = Math.max((endTime - now) / duration, 0);
            var value = Math.round(end - (remaining * range));
            // replace numeric digits only in the original string
            obj.innerHTML = textStarting.replace(/([0-9]+)/g, value);
            if (value == end) {
                clearInterval(timer);
            }
        }

        timer = setInterval(run, stepTime);
        run();
    }
}

animateValue(document.getElementById('value'));
#value {
    font-size: 50px;
}
<div id="value">+300% gross margin</div>

Answer

This works well. However, I needed to use a comma within the number. Below is the updated code which checks for commas. Hope someone finds this useful if they stumble across this post.

function animateValue(id, start, end, duration) {

    // check for commas
    var isComma = /[0-9]+,[0-9]+/.test(end); 
    end = end.replace(/,/g, '');

    // assumes integer values for start and end

    var obj = document.getElementById(id);
    var range = end - start;
    // no timer shorter than 50ms (not really visible any way)
    var minTimer = 50;
    // calc step time to show all interediate values
    var stepTime = Math.abs(Math.floor(duration / range));

    // never go below minTimer
    stepTime = Math.max(stepTime, minTimer);

    // get current time and calculate desired end time
    var startTime = new Date().getTime();
    var endTime = startTime + duration;
    var timer;

    function run() {
        var now = new Date().getTime();
        var remaining = Math.max((endTime - now) / duration, 0);
        var value = Math.round(end - (remaining * range));
        obj.innerHTML = value;
        if (value == end) {
            clearInterval(timer);
        }
        // Preserve commas if input had commas
        if (isComma) {
            while (/(\d+)(\d{3})/.test(value.toString())) {
                value = value.toString().replace(/(\d+)(\d{3})/, '$1'+','+'$2');
            }
        }
    }

    var timer = setInterval(run, stepTime);
    run();
}

animateValue("value", 100, 25, 2000); 
Answer

HTML

<!DOCTYPE html>
<html>
<head>
    <title>Count</title>
</head>
<body>
    <div id="value">1000</div>
</body>
</html>

JAVASCRIPT snippet

Here is a simple js function decrementing values from a given start number to an end number (object prototype)..

function getCounter(startCount,endcount,time,html){
objects = {
    //you can alternateif you want yo add till you reach the endcount
    startCount:startCount,
    endCount:endcount,
    timer:time
}
this.function = function(){
    let startTm  = objects.startCount,
        timer = objects.timer,
        endCount = objects.endCount;
        //if you want it to add a number just replace the -1 with +1
        /*and dont forget to change the values in the object prototype given a variable of counter*/
    let increament = startTm  < endCount ? 1:-1;
        timmer  = setInterval(function(){
                startTm  += increament;
                html.innerHTML = startTm ;
                if(startTm  == endCount){
                    clearInterval(timmer);
                }
            },timer);
   }
}
// input your startCount,endCount  the timer.....
let doc = document.getElementById('value');

let counter = new getCounter(1000,1,10,doc);
//calling the function in the object
counter.function();

Check out this demo https://jsfiddle.net/NevilPaul2/LLk0bzvm/

Answer

Current solutions do update more often than needed. Here a frame based approach, which is accurate:

function animateValue(obj, start, end, duration) {
  let startTimestamp = null;
  const step = (timestamp) => {
    if (!startTimestamp) startTimestamp = timestamp;
    const progress = Math.min((timestamp - startTimestamp) / duration, 1);
    obj.innerHTML = Math.floor(progress * (end - start) + start);
    if (progress < 1) {
      window.requestAnimationFrame(step);
    }
  };
  window.requestAnimationFrame(step);
}

const obj = document.getElementById('value');
animateValue(obj, 100, -25, 2000);
div {font-size: 50px;}
<div id="value">100</div>

Answer

This is what i came up with:

function animateVal(obj, start=0, end=100, steps=100, duration=500) {   
    start = parseFloat(start)
    end = parseFloat(end)

    let stepsize = (end - start) / steps
    let current = start
    var stepTime = Math.abs(Math.floor(duration / (end - start)));
    let stepspassed = 0
    let stepsneeded = (end - start) / stepsize

    let x = setInterval( () => {
            current += stepsize
            stepspassed++
            obj.innerHTML = Math.round(current * 1000) / 1000 
        if (stepspassed >= stepsneeded) {
            clearInterval(x)
        }
    }, stepTime)
}   

animateVal(document.getElementById("counter"), 0, 200, 300, 200)
Answer

Here is one version where increments grow by some defined multiplier (mul). frameDelay is the time delay for each increment. This looks a bit better if you have values that camn

function cAnimate(id, start, end, frameDelay = 100, mul = 1.2) {
    var obj = document.getElementById(id);
    var increment = 2;
    var current = start;
    var timer = setInterval(function() {
        current += increment;
        increment *= mul;
        if (current >= end) {
            current = end;
            clearInterval(timer);
        }

        obj.innerHTML = Math.floor(current).toLocaleString();

    }, frameDelay);
}

cAnimate("counter", 1, 260000, 50);
Answer

I used a mixture of all of these to create a function that updates a BehaviorSubject.

function animateValue(subject, timerRef, startValue, endValue, duration){
  if (timerRef) {  clearInterval(timerRef); }
  const minInterval = 100;
  const valueRange = endValue - startValue;
  const startTime = new Date().getTime();
  const endTime = startTime + (duration * 1000);
  const interval = Math.max((endTime-startTime)/valueRange, minInterval);

  function run() {
    const now = new Date().getTime();
    const rangePercent = Math.min(1-((endTime-now)/(endTime-startTime)),1);
    const value = Math.round(rangePercent * valueRange+startValue);

    subject.next(value);
    if (rangePercent >= 1) {
      clearInterval(timerRef);
    }
  }

  timerRef = setInterval(run, interval);
  run();
}

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