//get the server date
this.service.getServerTime().subscribe(serverDate => {
    this.serverDate = serverDate;
}, error => { });

//start the timer using observable
let timer = Observable.timer(1000, 1000);
this.timerSubscription = timer.subscribe((t: any) => {
    this.timerExecuted();
});

private timerExecuted(): void {
    if (!this.serverDate) {
        return;
    }
    //add 1 second to the server date
    this.serverDate.setSeconds(this.serverDate.getSeconds() + 1);

    //console log the server date after adding 1 second
    console.log(this.serverDate);
}