Is it possible to get the current system time dynamically on Angular without using a backend service-CodePudding

As the title says, I want the current system time.
I know that using Date() can give me the current time, but that isn't necessarily the system time so it doesn't help.

I know I can use http request for getting the system time from some backend service, but the problem is that I want the system time to be updated dynamically (if system time changes - I expect my web page to change the time even if I don't refresh the page).
So if there's a way to achieve this using angular only - it will be much easier.

Is it possible to do so?

Example:
I'm using Linux machine, and now I set the current date to be 1 Feb 2022, 03:12:20 like this:

sudo date -s "1 FEB 2022 03:12:20"

So now I expect my web page to display the same date and time - 1 FEB 2022 03:12:20

CodePudding user response：

you can use a rxjs operator and map

date$=timer(0,1000).pipe(map(_=>new Date()))
{{date$|async}}

But this only give you the date in the client. If you want the date in server you need make a call to the server to correct

So you can has some like

  incr:number=0;
  date$=timer(0,1000).pipe(
    switchMap((i:number)=>{
      if (i==0)  //you can indicate here when you want "check"
                    //the date in server,e.g. each 10 seconds
      {
        return this.service.getDate().pipe(tap(x=>{
        this.incr=x.getTime()-new Date().getTime()}))
        }
      return of(new Date(new Date().getTime() this.incr))
  }))

CodePudding user response：

didn't test it, but new Date() should always give you the system time, meaning that you could just get new Date() every second.

this roughly translates to:

If no arguments are given, the constructor creates a date object with the date and time of the current system time zone

so the solution would be:

document.setInterval(() => console.info(new Date()), 1000);

or maybe more angularly (using rxjs instead of vanilla)

timer(1000).subscribe(() => console.info(new Date());