gistfile1.txt

var TeaTime = function( year, month, day, hour, minute, second ) {
  this.year = year; this.month = month; this.day = day;
  this.hour = hour; this.minute = minute; this.second = second;

  var start = new Date(
    this.year, this.month-1, this.day,
    this.hour, this.minute, this.second
  );

  var now = new Date();
  this.diff = now.getTime() - start.getTime();
}

TeaTime.prototype.getElapsedTime = function() {
   var diff = this.diff / 1000;

   var dH = parseInt(diff / 3600);
   var dM = parseInt((diff / 60) % 60);
   var dS = parseInt(diff % 60);

   return [dH, dM, dS];
}

TeaTime.prototype.getFormattedTimer = function() {
  var dT = this.getElapsedTime();
  var fmt_pad = function( num, pad ) {
    var res = '' + num; // to_string
    while( res.length < pad ) {
      res = '0' + res;
    }
    return res;
  }

  var res = fmt_pad( dT[0], 2 ) + ':' +
    fmt_pad( dT[1], 2 ) + ':' +
    fmt_pad( dT[2], 2 );

  return res;
}


var time = new TeaTime( 2012, 2, 15, 20, 0, 0 );

console.log( time.getElapsedTime() );
console.log( time.getFormattedTimer() );

// (Now: ... 03:13:48 );