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Stupid Easy Javascript Authentication

To authenticate users using Facebook Login with JavaScript, you can utilize the Facebook JavaScript SDK. The SDK provides methods to handle user authentication and retrieve user information once they have logged in. Here’s a step-by-step guide on how to achieve this:

Create a Facebook App

1. Go to the Facebook Developer website (https://developers.facebook.com/) and create a new app.

2. In your app dashboard, note down the App ID, as you’ll need it later.

Load the Facebook JavaScript SDK

Add the following script tag to your HTML file, preferably just before the closing </body> tag.

<script async defer crossorigin="anonymous" src="https://connect.facebook.net/en_US/sdk.js"></script>

Initialize the Facebook SDK

lace the following code just after the SDK script tag to initialize it with your App ID

<script>
  window.fbAsyncInit = function() {
    FB.init({
      appId: 'YOUR_APP_ID',
      cookie: true,
      xfbml: true,
      version: 'v11.0'
    });
  };

  // Load the SDK asynchronously
  (function(d, s, id) {
    var js, fjs = d.getElementsByTagName(s)[0];
    if (d.getElementById(id)) return;
    js = d.createElement(s); js.id = id;
    js.src = "https://connect.facebook.net/en_US/sdk.js";
    fjs.parentNode.insertBefore(js, fjs);
  }(document, 'script', 'facebook-jssdk'));
</script>

Create a Login Button

Add a login button to your HTML page to trigger the Facebook Login dialog.

<button onclick="loginWithFacebook()">Login with Facebook</button>

Implement the Login Function

Define the loginWithFacebook a function that will handle the Facebook Login process.

<script>
  function loginWithFacebook() {
    FB.login(function(response) {
      if (response.authResponse) {
        // User successfully logged in
        getUserDetails();
      } else {
        console.log('User cancelled login or did not fully authorize.');
      }
    }, { scope: 'public_profile,email' });
  }

  function getUserDetails() {
    FB.api('/me', { fields: 'id,name,email' }, function(response) {
      console.log('User details:', response);
      // Here, you can use the retrieved user information as needed.
    });
  }
</script>

Handle Logout

If you want to provide a logout option, add a button with a logoutWithFacebook function to handle the logout process.

<script>
  function loginWithFacebook() {
    FB.login(function(response) {
      if (response.authResponse) {
        // User successfully logged in
        getUserDetails();
      } else {
        console.log('User cancelled login or did not fully authorize.');
      }
    }, { scope: 'public_profile,email' });
  }

  function getUserDetails() {
    FB.api('/me', { fields: 'id,name,email' }, function(response) {
      console.log('User details:', response);
      // Here, you can use the retrieved user information as needed.
    });
  }
</script>

That’s it! With this setup, when users click the “Login with Facebook” button, a popup window will appear, allowing them to log in to your application using their Facebook credentials. Once logged in, you can retrieve and utilize the user’s Facebook data. Remember that you should handle the user’s data responsibly and in accordance with Facebook’s policies and user consent.

Please note that the SDK versions and available fields might change over time, so it’s essential to refer to the official Facebook Developer documentation for any updates: https://developers.facebook.com/docs/javascript/


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Albert Guerrero

Software Engineer | AppSec | Military Veteran

By Albert Guerrero

Software Engineer | AppSec | Military Veteran

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