Get previous route Angular 7

If you just want the previous route you can create an observable like this

 public previousRoute$: Observable<string> = this.router.events.pipe(
   filter((e) => e instanceof RoutesRecognized),
   pairwise(),
   map((e: [RoutesRecognized, RoutesRecognized]) => e[0].url)
 );

Now you can subscribe this observable and perform any action (Make sure you unsubscribe this observable on OnDestroy event.)

this.previousRoute$.subscribe(url => {
  //perform your action
});

NOTE: This observable will start emitting event when user is on 2nd navigation.

Use angular's Location service, it is inbuilt to angular and import it from '@angular/common' like this:

import { Component, OnInit, Input } from '@angular/core';
import { ActivatedRoute } from '@angular/router';
import { Location } from '@angular/common';

import { Hero }         from '../hero';
import { HeroService }  from '../hero.service';

@Component({
  selector: 'app-hero-detail',
  templateUrl: './hero-detail.component.html',
  styleUrls: [ './hero-detail.component.css' ]
})
export class HeroDetailComponent implements OnInit {
  @Input() hero: Hero;

  constructor(
    private location: Location
  ) {}

  goBack() {
    this.location.back();
  }   
}

And then use location.back() to goto previous page. This is a working example:

https://stackblitz.com/angular/qvvrbgrmmda