页面刷新/重新加载后不显示警报(Angular v10)

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class AlertService {
  private showAlert: boolean = false;

  constructor() { }

  setShowAlert(value: boolean) {
    this.showAlert = value;
  }

  getShowAlert() {
    return this.showAlert;
  }
}

import { Component, OnInit } from '@angular/core';
import { AlertService } from 'path/to/alert.service';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent implements OnInit {
  showAlert: boolean = false;

  constructor(private alertService: AlertService) { }

  ngOnInit() {
    this.showAlert = this.alertService.getShowAlert();
  }

  closeAlert() {
    this.showAlert = false;
    this.alertService.setShowAlert(false);
  }
}

import { Injectable } from '@angular/core';
import { Router, NavigationEnd } from '@angular/router';
import { AlertService } from 'path/to/alert.service';

@Injectable({
  providedIn: 'root'
})
export class AlertGuard {
  constructor(private router: Router, private alertService: AlertService) {
    this.router.events.subscribe(event => {
      if (event instanceof NavigationEnd) {
        this.alertService.setShowAlert(true);
      }
    });
  }
}

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';
import { ExampleComponent } from './example.component';
import { AlertGuard } from 'path/to/alert.guard';

const routes: Routes = [
  {
    path: 'example',
    component: ExampleComponent,
    canActivate: [AlertGuard] // 添加路由守卫
  }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }