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Anubhav Sharma
Anubhav Sharma

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The Anubhav portal was launched in March 2015 at the behest of the Hon'ble Prime Minister for retiring government officials to leave a record of their experiences while in Govt service .

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1 Answers

Ravi Vishwakarma
Ravi Vishwakarma 16 Dec 2025
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In Angular, a service is a reusable class used to share data, logic, or functionality across components. It helps keep components clean, lightweight, and focused on the UI.

What is a Service in Angular?

An Angular service is:

  • A TypeScript class
  • Used to handle business logic
  • Used for data access (API calls)
  • Used for state sharing between components
  • Independent of UI
  • Services are typically injected into components using Dependency Injection (DI).

Why do we need Services?

Without services:

  • Components become large and hard to maintain
  • Logic gets duplicated
  • Data sharing between components becomes messy

With services:

  • Logic is centralized
  • Code is reusable
  • Components are loosely coupled
  • Easier to test and maintain

Simple Service Example

Create a service

ng generate service user

This creates:

user.service.ts

Service code

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

@Injectable({
  providedIn: 'root'
})
export class UserService {
  getUsers() {
    return ['Alice', 'Bob', 'Charlie'];
  }
}

@Injectable() explained

  • Marks the class as a service
  • Allows Angular to inject dependencies
  • providedIn: 'root' → service is singleton (one instance for the whole app)

Using Service in a Component

import { Component, OnInit } from '@angular/core';
import { UserService } from './user.service';

@Component({
  selector: 'app-user',
  template: `
    <ul>
      <li *ngFor="let user of users">{{ user }}</li>
    </ul>
  `
})

export class UserComponent implements OnInit {

  users: string[] = [];

  constructor(private userService: UserService) {}

  ngOnInit(): void {
    this.users = this.userService.getUsers();
  }
}

Real-world Example: API Call Service

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class ProductService {

  private apiUrl = 'https://api.example.com/products';

  constructor(private http: HttpClient) {}

  getProducts() {
    return this.http.get(this.apiUrl);
  }
}

Component usage

this.productService.getProducts().subscribe(data => {
  this.products = data;
});

Service Scope (Where it lives)

1. App-level (Singleton)

@Injectable({ providedIn: 'root' })

One instance for entire app

2. Module-level

providers: [UserService]

One instance per module

3. Component-level

@Component({
  providers: [UserService]
})

New instance per component

Common Uses of Services

  • HTTP / API communication
  • Authentication & Authorization
  • Logging
  • Shared state management
  • Utility functions
  • WebSocket / SSE handling

Services and Dependency Injection

Angular automatically:

  • Creates the service
  • Manages its lifecycle
  • Injects it where needed
constructor(private authService: AuthService) {}

Service vs Component

Component Service
Handles UI Handles logic/data
Has template & styles No template
Tied to view Reusable across app

Best Practices

  • Keep components thin
  • Move logic to services
  • Use services for API calls
  • Avoid storing UI logic in services
  • Use providedIn: 'root' unless scope is needed

Summary

  • Service = reusable logic/data holder
  • Promotes clean architecture
  • Injected using Dependency Injection
  • Essential for scalable Angular apps
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