为什么Angular在app.modules.ts中导出空类? [英] Why Angular export empty class in app.modules.ts?

问题描述

我是Angular的新手，正在使用Angular 4，并且通过ng new命令使用Angular CLI创建了一个应用程序.

I am new in Angular, I am using Angular 4, and I made an app using the Angular CLI, by ng new command.

在main.ts中，我们有

In main.ts, we have

 ...
import {AppModule} from './app/app.module';
 .
 .
platformBrowserDynamic().bootstrapModule(AppModule);

和AppModule在app/app.module中定义(如您所见)，这是我们在app.module.ts中拥有的内容:

and AppModule is defined (as you see) in app/app.module, here is what we have in app.module.ts:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';

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

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

如您所见，它显示为export class AppModule { }，它也用在platformBrowserDynamic().bootstrapModule(AppModule);

As you see it says export class AppModule { }, and it also used in platformBrowserDynamic().bootstrapModule(AppModule);

有人可以帮我解释一下吗?

Can someone please explain this for me?

推荐答案

该类的主体确实为空.但是类(@NgModule)上方的装饰器正在为该类提供其功能.因此，实际上，该类并不为空.在将装饰器应用到它之后，它不需要任何额外的逻辑. bootstrapModule将一个类作为输入，并假定该类已用@NgModule装饰，并以与您所拥有的类似的方式(声明，导入，提供者等)进行装饰.

The body of the class is indeed empty. But that decorator above the class (@NgModule) is giving that class its functionality. So really, that class isn't empty. It just doesn't require any extra logic after the decorator is applied to it. bootstrapModule takes a class as input and assumes that that class is decorated with @NgModule configured in a manner similar to what you have (declarations, imports, providers, etc.).

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