angular - Receiving multiple instances of data from Behavior Subject every time component is initialised -

i have simple router calling service , receiving data behavior subject...when navigate route , comeback receiving multiple values subject...how can destroy observers of subject , create new subject whenever need...? here plunker demo http://plnkr.co/edit/okiljcekskho1zjf5may?p=preview
planning destroy observers of subject in ngondestroy...

  ngondestroy(){ this.srvc.destroysubject();  } 

can please tell me how destroy observers of behaviorsubject?

the behavior expected.

export class sample1 {   constructor(public srvc:heroservice) {       this.srvc.data.subscribe(data=> {         console.log(data);       });       this.srvc.getdata();   } } 

in constructor subscribe srvc.data , because data behaviorsubject returns recent emitted value. initialize data null, therefore @ first there no data.

then in constructor call this.srvc.getdata() causes event emitted , received subscription (the lines before).

if navigate away , back, sample1 initialized again , constructor executed. first thing is subscribes srvc.data. , gets last emitted value received data previous call getdata() (when first navigated heroes).

the next thing call this.srvc.getdata() again emits received data , subscription gets value passed.

workaround

to fix move call this.srvc.getdata(); service instead like

@injectable() export class heroservice {   data: behaviorsubject<repairorder> = new behaviorsubject(null);    constructor() {     this.getdata();   }    getdata(){     this.data.next('recieved data');   }   destroysubject(){     //alert('hi');   } } 

plunker example