This Angular code provides an AuthService that handles user login by making a POST request to a server and returning an observable with the login result.

Run example

npm run import -- "Authentication service"

Authentication service

import {Observable} from 'rxjs/Observable';
import {Http} from '@angular/http';
import {Injectable} from '@angular/core';

export let callbackUrl = 'localhost';

@Injectable()
export class AuthService {
    http: Http

    constructor(public
) {
}

login(username
:
string, password
:
string
):
Observable < number > {
    return this.http.post(callbackUrl, {username, password})
        .map(r => r.json());
}
}

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

const CALLBACK_URL = 'http://localhost:4200'; // Use a constant for the URL

@Injectable()
export class AuthService {
  private readonly http: HttpClient;

  constructor(http: HttpClient) {
    this.http = http;
  }

  /**
   * Performs a POST request to the callback URL with the provided username and password.
   * @param username The username to login with
   * @param password The password to login with
   * @returns An Observable containing the response from the server
   */
  login(username: string, password: string): Observable {
    // TODO: Handle server-side errors, e.g. validate username and password
    // TODO: Implement authentication logic (e.g. check username and password against a database)
    return this.http.post(CALLBACK_URL, { username, password })
     .map(response => response);
  }
}

This Angular code defines a service (AuthService) responsible for handling user authentication.

Here's a breakdown:

1. Imports:

   • Imports Observable from RxJS for handling asynchronous operations.
   • Imports Http from Angular's HTTP module for making network requests.
   • Imports Injectable from Angular's core module to mark the class as a service.

2. callbackUrl:

   • Defines a constant callbackUrl with a default value of 'localhost'. This likely represents the URL where the authentication server will redirect the user after successful login.

3. AuthService:

   • Defines a class AuthService decorated with @Injectable(), making it injectable into other components.
   • http: An instance of Http is injected into the constructor.

4. login() Method:

   • Takes username and password as input parameters.
   • Makes a POST request to callbackUrl with the username and password as JSON data using this.http.post().
   • Uses map() to transform the response from the server into JSON format.
   • Returns an Observable<number> representing the result of the login attempt. The type number suggests that the server might return a numerical status code or an ID.

In summary: This code defines a basic authentication service that handles user login by sending credentials to a server and returning an observable representing the login result.