making increments smaller

accellerating-decromancer.js

var decremancer = function(iterations, unit, time) {
    for (var i = 0; i < iterations; i++) {
        //set increments to `unit`
    }
    
    //where you'd determine the rate things get smaller
    var newTime = time - 100;
    //stop when the time gets too small
    if (newTime < 0) return;
    //DECROMANCE
    var newUnit = unit - 1;
    setTimeout( function(){
        decremancer(iterations, newUnit, newTime)
    }, newTime);
}

var iterations = 200;
var unit = 20;
var time = 2000;
// kick things off
decremancer();

decromancer.js

var decremancer = function(iterations, unit) {
    for (var i = 0; i < iterations; i++) {
        //set increments to `unit`
    }
}

var time = 2000;
var _unit = 20;
//setting interval to a variable is helpful for cancelling it at some point
var interval = setInterval(function(){
    if (_unit -1 < 0) return;
    
    unit = _unit - 1;
    decremancer(20, unit);
}, time);