unsubscribe an existing subscription before creating a new one (avoids jumps in session timer in case of multiple query on one page)

ui/hv2-ui/src/app/token.service.ts

@@ -1,10 +1,10 @@
 import { Injectable } from '@angular/core';
 import { MessageService } from './message.service';
-import { HttpClient, HttpHeaders } from '@angular/common/http';
+import { HttpClient } from '@angular/common/http';
 import { UserCreds } from './userCreds'
 import jwt_decode  from 'jwt-decode'
 import { Observable, interval, Subject, Subscription } from 'rxjs'
-import { map, takeUntil, takeWhile } from 'rxjs/operators'
+import { map, takeWhile } from 'rxjs/operators'
 import { authserviceBaseUrl } from './config'
 
 
@@ -22,6 +22,7 @@ export class TokenService {
   public static Id_RefreshToken_Key : string = "id_refreshtoken";
 
   private _expiryTime =  new Subject<number>()
+  private subscription: Subscription
 
   constructor(private http: HttpClient, private messageService: MessageService) {
   }
@@ -56,7 +57,10 @@ export class TokenService {
     let exp = jwt_decode(token)["exp"]
     let iat = jwt_decode(token)["iat"]
     let start = exp - iat
-    interval(1000).pipe(map(v => start - v)).pipe(takeWhile(v => v != 0)).subscribe(v => this._expiryTime.next(v))
+    if (this.subscription && !this.subscription.closed) {
+      this.subscription.unsubscribe()
+    }
+    this.subscription = interval(1000).pipe(map(v => start - v)).pipe(takeWhile(v => v != 0)).subscribe(v => this._expiryTime.next(v))
   }
 
   async login(login: string, password: string) : Promise<void> {