Angular2 Check if Location.back has history to go back?

You can use JavaScript to view the last place the user visited:

document.referrer

doc

So, in your case, you can check if the user can go back, as follows:

historyBack() {
if (document.referrer) {
  this._location.back();
 }
}

In Angular 7 you can use Router.navigated property to check if any navigation event has occurred.

constructor(
  private router: Router,
  private location: Location
) {
  this.hasHistory = this.router.navigated;
}

Tried many solutions out there-

1. this.router.navigated always returned true for some reason (maybe because I'm navigating to another page via redirectTo in routing).
2. I tried with history.length but that always returned 2.
3. Then tried to use history.state to check if doesn't contain any arbitrary data, then I can assume it's a fresh tab open without any history. But it was only setting {navigationId: 1} (by Angular) so was not useful when refreshing an existing tab with existing history.

Finally, I thought of using sessionStorage this way which is working fine for me.

In a global space (let's say in app.component.ts), I did this-

ngOnInit(): void {
    this.router.events.pipe(
        filter(event => event instanceof NavigationEnd),
    ).subscribe(() => {
        let navigations = parseInt(sessionStorage.getItem('totalNavigations'), 10) || 0;
        navigations++;
        sessionStorage.setItem('totalNavigations', navigations.toString());
    });
}

Now, when I want to go back to see if there is any history, I'm doing this-

goBack(): void {
    const totalNavigations = parseInt(sessionStorage.getItem('totalNavigations'), 10);
    if (totalNavigations > 1) {
        this.location.back();    // Or history.back()
    } else {
        this.router.navigateByUrl('/my-default-path')
    }
}