getDifference(date_posted: number): string{
    var ret = '';
    var time = Math.abs(date_posted - Date.now());
    var weeks = 0, days = 0, hours = 0, minutes = 0;
    if(time >= this.one_week){
      weeks = Math.abs(Math.floor(time / this.one_week));
      time = time % this.one_week;
    }
    if(time >= this.one_day){
      days = Math.abs(Math.floor(time / this.one_day));
      time = time % this.one_day;
    }
    if(time >= this.one_hour){
      hours = Math.abs(Math.floor(time / this.one_hour));
      time = time % this.one_hour;
    }
    minutes = Math.abs(Math.round(time / this.one_minute));

    if(weeks > 0){
      ret = weeks + " w " + days + " d ago";
    }
    else if(days > 0){
      ret = days + " d " + hours + " h ago";
    }
    else if(hours > 0){
      ret = hours + " h " + minutes + " m ago";
    }
    else{
      ret = minutes + " m ago";
    }
    return ret;
  }