How to do token authentication in angular??

Token-based authentication is a common method for authenticating users in a web application. In Angular, you can use the HttpClient module to make HTTP requests to a backend server and include an authentication token in the request header.

Here is an example of how you might implement token-based authentication in an Angular application:

On the backend server, create a route that accepts a username and password and returns an authentication token if the credentials are valid.

In the Angular application, create a login form for the user to enter their username and password.

When the user submits the form, use the HttpClient module to send a request to the backend server with the username and password.

If the backend server returns a successful response, store the authentication token in a secure location, such as an HttpOnly cookie or the browser’s local storage.

On subsequent requests to the backend server, include the authentication token in the request header.

import { HttpClient, HttpHeaders } from '@angular/common/http';

const loginUrl = 'http://example.com/login';
const data = { username: 'user', password: 'password' };

const httpOptions = {
  headers: new HttpHeaders({ 'Content-Type': 'application/json' }),
};

const result = await this.http.post<any>(loginUrl, data, httpOptions).toPromise();

if (result.success) {
  // Store the token in a secure location
  localStorage.setItem('authToken', result.token);
}

On the backend server, verify the authenticity of the token on each protected route or API endpoint. If the token is invalid or has expired, return an error response.

I hope this helps! Let me know if you have any questions.