Bootstrapping Providers
The bootstrap process also starts the dependency injection system in Angular 2. We won't go over Angular 2's dependency injection system here - that is covered later. Instead let's take a look at an example of how to bootstrap your application with application-wide providers.
For this, we will register a service called Greeter with the providers property of the module we are using to bootstrap the application.
app/app.module.ts
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } '@angular/core';
import { MyApp } from './app.component'
import { Greeter } from './greeter.service';
@NgModule({
imports: [BrowserModule],
providers: [Greeter],
declarations: [MyApp],
bootstrap: [MyApp]
})
export class MyAppModule {
}