timer.js

_startTimer(){
    this._stopTimer();
    let timeSeconds = 1;
    this._timerInterval = this.$interval(() => {
        timeSeconds += 1;
        this.onlineTimeText = this._formatTime(timeSeconds);
    }, 1000);
    this.onlineTimeText = this._formatTime(timeSeconds)
}
_stopTimer(){
    this.$interval.cancel(this._timerInterval);
    this.onlineTimeText = "";
}
_formatTime(seconds){
    const displayZero = value => value < 10 ? "0"+value : String(value);
    const displaySeconds = displayZero(seconds%60);
    const minutes = Math.floor(seconds/60);
    const displayMinutes = displayZero(minutes%60);
    const hours = Math.floor(minutes/60);
    if (hours) return `${hours}:${displayMinutes}:${displaySeconds}`;
    else return `${displayMinutes}:${displaySeconds}`;
}