基本页面崩溃

app.component.html

<h1>Anguilar</h1>
<dd-button></dd-button>

应用模块ts

import { DdButtonComponent } from './ddButton.component';
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

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

@NgModule({
  declarations: [
    AppComponent,
    DdButtonComponent
  ],
  imports: [
    BrowserModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

ddButton.component.ts

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

@Component({
  selector: 'dd-button',
  template: "<dd-button>Text</dd-button>"
})
export class DdButtonComponent {
}

app.component.ts

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

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Explaining Modernity';
}

抱歉,可能的noobish问题,但由于没有错误,我有一个困难的时间寻找什么可能是导致问题。再描述一下崩溃,当我用 localhost:4200 它尝试加载并挂起几秒钟,然后在Firefox中出现“页面崩溃”页面。