angular2 官网案例 为什么路径闪烁

Question

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule }   from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
// Imports for loading & configuring the in-memory web api
import { HttpClientModule } from '@angular/common/http';
import { HttpClientInMemoryWebApiModule } from 'angular-in-memory-web-api';
import { InMemoryDataService }  from './in-memory-data.service';

import { AppComponent }         from './app.component';
import { DashboardComponent }   from './dashboard.component';
import { HeroesComponent }      from './heroes.component';
import { HeroDetailComponent }  from './hero-detail.component';
import { HeroService }          from './hero.service';
import { HeroSearchComponent }  from './hero-search.component';


@NgModule({
  imports: [
    BrowserModule,
    FormsModule,
    HttpClientModule,
    //forRoot()配置方法需要InMemoryDataService类实例，用来向内存数据库填充数据
    HttpClientInMemoryWebApiModule.forRoot(InMemoryDataService),
    AppRoutingModule
  ],
  declarations: [ 
    AppComponent,
    DashboardComponent,
    HeroDetailComponent,
    HeroesComponent,
    HeroSearchComponent
  ],
  providers: [ HeroService ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

import { NgModule }             from '@angular/core';
import { RouterModule, Routes } from '@angular/router';

import { DashboardComponent }   from './dashboard.component';
import { HeroesComponent }      from './heroes.component';
import { HeroDetailComponent }  from './hero-detail.component';

const routes: Routes = [
  { path: '', redirectTo: '/dashboard', pathMatch: 'full' },
  { path: 'dashboard',  component: DashboardComponent },
  { path: 'detail/:id', component: HeroDetailComponent },
  { path: 'heroes',     component: HeroesComponent }
];

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