hello.component.ts

import { HttpClient } from '@angular/common/http';
import { Component, Input, OnDestroy, OnInit } from '@angular/core';
import { Subject } from 'rxjs';
import { takeUntil } from 'rxjs/operators';

@Component({
  selector: 'hello',
  template: `<h1>Hello!</h1>`,
  styles: [`h1 { font-family: Lato; }`]
})
export class HelloComponent implements OnInit, OnDestroy  {
$unsubscribe = new Subject<void>();

constructor(private http: HttpClient) {}

  ngOnInit() {
    this.getData()
  }

  getData() {
    this.http.get('some-endpoint')
    .pipe(takeUntil(this.$unsubscribe))
    .subscribe(response => console.log(response))
  }

  ngOnDestroy() {
    this.$unsubscribe.next();
    this.$unsubscribe.complete()
  }
}