Timer.js - AMD module used for accurate, long timers

timer.js

define([
  "namespace",
  // Libs
  "use!jquery",
  "use!backbone"
  // Modules
  // Plugins
  ], 
function( namespace, $, Backbone ) {

  // Create a new module
    var Timer = namespace.module(),
        app = namespace.app;

    var defaults = {
      "length" : 5000,
      "resolution" : 20,
      "ontick": function(){},
      "oncomplete": function(){}
    }


  // =============================================================== Start
    // see http://www.sitepoint.com/creating-accurate-timers-in-javascript/ for inspiration

    Timer.start = function ( options ){
      var length      = options.length     || defaults.length,
          resolution  = options.resolution || defaults.resolution,
          ontick      = options.ontick     || defaults.ontick,
          oncomplete  = options.oncomplete || defaults.oncomplete;

      var steps = ( length / 100 ) * ( resolution / 10 ),
          speed = length / steps,
          count = 0,
          start = new Date().getTime();

      function tick(){
        if( count++ == steps ){
          oncomplete( steps, count );
        } else {
          ontick( steps, count );
          var diff = ( new Date().getTime() - start ) - ( count * speed );
          window.setTimeout( tick, ( speed - diff ) );
        }
      }
      window.setTimeout( tick, speed );
    }

  // ============================================================================== VIEWS
  

  return Timer;
});