title: Angular/RxJS: Max number of subscriptions?
body: <p>I'm creating a directive that formats a date based on the user's timezone. The user has the option to update their timezone via a settings dropdown on the page. Therefore, the directive is subscribing to timezone updates and updating on change.</p>
  <pre><code>ngOnInit() {
      this.timezoneUpdatedSubscription = this.commonService.timezoneUpdated.subscribe(() =&gt; {
          this.el.nativeElement.innerHTML = moment(this.localDate).tz(this.commonService.usersTimezone).format(this.format);
      })
  }
  
  ngOnDestroy() {
      if (this.timezoneUpdatedSubscription) {
          this.timezoneUpdatedSubscription.unsubscribe();
      }
  }
  </code></pre>
  <p>The possible issue is that this directive might be used a large number of times on a page, likely 50 times but possibly 200+ times at times. This means there could be 200+ subscriptions at a time.</p>
  <p>Would this cause a performance issue with a large number of elements being updated at once? I couldn't see any documentation to suggest either way.</p>