how to unsubscribe observable in angular 8 code example

Example 1: angular unsubscribe from observable

//Please note that there are many ways to unsubscribe, this is one of them
import { Subscription } from 'rxjs';

private searchEventSubscription: Subscription;

export class someComponent OnInit, OnDestroy {

    constructor(private someService: SomeService) { }

    ngOnInit() {
      this.searchEventSubscription = this.someService.someMethod.subscribe(result => {  
        doSomething(result);
      });
    }

    ngOnDestroy() {
		this.searchEventSubscription.unsubscribe()
    }

Example 2: how to unsubscribe from observable created by http

import { Component, OnInit, OnDestroy } from '@angular/core';
import { HttpClient } from '@angular/common/http';

import { Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';

interface User {
  id: string;
  name: string;
  age: number;
}

@Component({
  selector: 'app-foobar',
  templateUrl: './foobar.component.html',
  styleUrls: ['./foobar.component.scss'],
})
export class FoobarComponent implements OnInit, OnDestroy {
  private user: User = null;
  private destroy$ = new Subject();

  constructor(private http: HttpClient) {}

  ngOnInit() {
    this.http
      .get<User>('api/user/id')
      .pipe(takeUntil(this.destroy$))
      .subscribe(user => {
        this.user = user;
      });
  }

  ngOnDestroy(): void {
    this.destroy$.next();  // trigger the unsubscribe
    this.destroy$.complete(); // finalize & clean up the subject stream
  }
}