RouterWithBackButtonService.ts

import Service, { inject as service } from "@ember/service";
import RouterService from "@ember/routing/router-service";

export default class RouterWithBackButtonService extends Service {
  @service("router")
  router!: RouterService;

  previousURL = "";

  setup() {
    this.router.on("routeWillChange", () => {
      this.previousURL = this.router.currentURL;
    });
  }

  goBack() {
    if (!this.previousURL) {
      return;
    }
    this.router.transitionTo(this.previousURL);
  }
}