Count animation from number A to B

Question

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

To make the whole thing a bit more alive,

Answer 1

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);