ตั้งค่า Injector กำหนด service class ใน provider เพื่อใช้งานใน Angular

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

import { AppComponent }  from './app.component';
import { UserComponent }  from './components/user.component';
import { StaffFormComponent }  from './components/staff-form.component';
import { StaffListComponent }  from './components/staff-list.component'

import { StaffService } from './components/staff.service'

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

import { Component } from '@angular/core'

import { Staff } from './staff'
import { StaffService } from './staff.service'

@Component({
  moduleId: module.id,    
  providers:[StaffService],
  selector: 'staff-list',
  templateUrl: `./staff-list.component.html`,
})
export class StaffListComponent {

}

this.staffs = staffService.getStaffs();

export class Staff {

  constructor(
    public id: number,
    public name: string,
    public department: string,
    public age?: number
  ) {  }

}