问如何在单击相同链接后刷新模板中的随机数？

EN

import { Component, OnInit } from '@angular/core';
import { Router, NavigationEnd } from '@angular/router';

@Component({
  selector: 'app-about',
  templateUrl: './about.component.html',
  styleUrls: ['./about.component.css']
})
export class AboutComponent implements OnInit {

  random;

  constructor(private router: Router) {
  console.log(this.router.onSameUrlNavigation);
    this.router.onSameUrlNavigation = 'reload'


    this.router.events.subscribe(event => {
      if (!(event instanceof NavigationEnd)) { return; }
      this.random = Math.random();
    });
  
  }

  ngOnInit() {


  }

}

<div class="page-header">
  <div class="container">
  <h1>Router Sample</h1>
  <div class="navLinks">

  <a [routerLink]="['/about']">About Us</a>

  </div>
  </div>
  </div>
  <div id="content">
  <div class="container">
  <router-outlet></router-outlet>
  </div>
  </div>

<h1>random : {{random}}</h1>
<p>
  about works!
</p>

//app modlule
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';

import { AppComponent } from './app.component';
import { AboutComponent } from './about/about.component';

const appRoutes: Routes = [
  { path: 'about', component: AboutComponent },
];

@NgModule({
  declarations: [
    AppComponent,
    AboutComponent
  ],
  imports: [
    RouterModule.forRoot(
      appRoutes,
      { enableTracing: true } // <-- debugging purposes only
    ),
    BrowserModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

//about.ts

import { Component, OnInit } from '@angular/core';
import { Router, NavigationEnd } from '@angular/router';
 
@Component({
  selector: 'app-about',
  templateUrl: './about.component.html',
  styleUrls: ['./about.component.css']
})
export class AboutComponent implements OnInit {
 
  random;
 
  constructor(private router:Router) {
    console.log("click route again");
    this.router.events.subscribe(event => {
      if(!(event instanceof NavigationEnd)) { return; }
      this.random = Math.random();
    });
   }
 
  ngOnInit() {

 
  }
 
}