Accurate Javascript setInterval replacement

interval.js

function Interval(func,duration){
  if(typeof func !== "function") throw new TypeError("Expected function");
  else if(typeof duration !== "number") throw new TypeError("Expected number");

  this.func = func;
  this.duration = duration;
  this.baseline = +new Date();

  (function(_this){
    _this.timer = setTimeout(function(){
      _this.run();
    },duration);
  })(this);
};
Interval.prototype.run = function(){
  this.func.call(window);
  this.baseline += this.duration;
 
  var nextTick = this.duration + this.baseline - new Date();
  if(nextTick<0) nextTick = 0;
  
  (function(_this){
    _this.timer = setTimeout(function(){
      _this.run();
    },nextTick);
  })(this);
};

Interval.prototype.stop = function(){
  clearTimeout(this.timer);
};

This code is a fork of manast's. It's an improvement over setInterval() as it keeps an internal clock that uses new Date() to preecisely track when setTimeout is off and adjusts, so the average of the offsets from the duration will be as close to 0 as possible. At least on my computer, setInterval() actually deviates less as it doesn't try to adjust to be correct, but it will end up being a couple of seconds off after a number of repeats.

Usage:

var interval = new Interval(function() {
  // do something
},100); // or whatever time

// do something
interval.stop();

// you can do this if you like...
interval.run();

Something interesting...

var time = +new Date(),
  interval = new Interval(function() {
    var n = +new Date();
    console.log(n - time);
    time = n;
  },duration);