For our new friends:

Every app needs authentication and authorization. Logto is an Auth0 alternative designed for modern apps and SaaS products.

In this article, we will go through the steps to quickly build the Google sign-in experience (user authentication) with Vanilla JS and  Logto.

Prerequisites

• A running Logto instance. Check out the introduction page to get started.
• Basic knowledge of Vanilla JS.
• A usable Google account.

Create an application in Logto

In you browser, open a new tab and enter the link of Logto Admin Console.

Once the page is loaded, in the "Get Started" section click the View all link to open the application framework list page.

Choose your application type

In the opening modal, scroll to the "Single page app" section or filter all the available " Single page app" frameworks using the quick filter checkboxes on the left.

Click the "Vanilla JS" framework card to start creating your application.

Enter application name

Enter the application name, e.g., "Bookstore," and click "Create application."

🎉 Ta-da! You just created your first application in Logto. You'll see a congrats page which includes a detailed integration guide. Follow the guide to see what the experience will be in your application.

Integrate Logto SDK

tip:

• The vanilla-js SDK is framework-agnostic, you can use it in any frontend framework by writing a wrapper to fit it.
• The sample project is available on our SDK repository.

Installation

Choose your favorite package manager or use the CDN to install the Logto Browser SDK.

npm

npm i @logto/browser

pnpm

pnpm add @logto/browser

yarn

yarn add @logto/browser

CDN

<!-- Special thanks to jsdelivr -->
<script type="module">
  import LogtoClient from 'https://cdn.jsdelivr.net/npm/@logto/[email protected]/+esm';
</script>

Init LogtoClient

Import and init a LogtoClient instance by passing config:

index.js

import LogtoClient from '@logto/browser';

const logtoClient = new LogtoClient({
  endpoint: '<your-logto-endpoint>',
  appId: '<your-application-id>',
});

The endpoint and appId can be found in the application details page in Logto Console.

Implement a sign-in and sign-out

Configure redirect URIs

Before we dive into the details, here's a quick overview of the end-user experience. The sign-in process can be simplified as follows:

1. Your app invokes the sign-in method.
2. The user is redirected to the Logto sign-in page. For native apps, the system browser is opened.
3. The user signs in and is redirected back to your app (configured as the redirect URI).

Regarding redirect-based sign-in

1. This authentication process follows the OpenID Connect (OIDC) protocol, and Logto enforces strict security measures to protect user sign-in.
2. If you have multiple apps, you can use the same identity provider (Logto). Once the user signs in to one app, Logto will automatically complete the sign-in process when the user accesses another app.

To learn more about the rationale and benefits of redirect-based sign-in, see Logto sign-in experience explained.

---

note:

In the following code snippets, we assume your app is running on http://localhost:3000/.

Configure redirect URIs

Switch to the application details page of Logto Console. Add a redirect URI http://localhost:3000/callback.

Just like signing in, users should be redirected to Logto for signing out of the shared session. Once finished, it would be great to redirect the user back to your website. For example, add http://localhost:3000/ as the post sign-out redirect URI section.

Then click "Save" to save the changes.

Handle redirect

There are still things to do after the user is redirected back to your application from Logto. Let's handle it properly.

pages/Callback.js

const callbackHandler = async (logtoClient) => {
  await logtoClient.handleSignInCallback(window.location.href);

  if (!logtoClient.isAuthenticated) {
    // Handle failed sign-in
    alert('Failed to sign in');
    return;
  }

  // Handle successful sign-in
  window.location.assign('/');
};

Implement sign-in and sign-out

logtoClient provides signIn and signOut methods to help you easily manage the authentication flow.

note:

Before calling .signIn(), make sure you have correctly configured Redirect URI in Admin Console.

pages/Home.js

const isAuthenticated = await logtoClient.isAuthenticated();

const onClickSignIn = () => {
  logtoClient.signIn('http://localhost:3000/callback');
};
const onClickSignOut = () => {
  logtoClient.signOut('http://localhost:3000');
};

const button = document.createElement('button');
button.innerHTML = isAuthenticated ? 'Sign Out' : 'Sign In';
button.addEventListener('click', isAuthenticated ? onClickSignOut : onClickSignIn);

document.body.appendChild(button);

Calling .signOut() will clear all the Logto data in memory and localStorage if they exist.

Handle authentication status

In Logto SDK, generally we can use logtoClient.isAuthenticated to check the authentication status, if the user is signed in, the value will be true, otherwise, the value will be false.

In your vanilla JS app, you can use the isAuthenticated status to programmatically show and hide the sign-in and sign-out buttons. Let's see how to do it.

const redirectUrl = 'http://localhost:3000/callback';
const baseUrl = 'http://localhost:3000';

// Conditional rendering of sign-in and sign-out buttons
const render = async (logtoClient) => {
  const isAuthenticated = await logtoClient.isAuthenticated();
  const container = document.querySelector('#container');

  const onClickSignIn = () => logtoClient.signIn(redirectUrl);
  const onClickSignOut = () => logtoClient.signOut(baseUrl);

  const button = document.createElement('button');
  button.innerHTML = isAuthenticated ? 'Sign Out' : 'Sign In';
  button.addEventListener('click', isAuthenticated ? onClickSignOut : onClickSignIn);

  container.append(button);
};

Test your integration:

Open your Vanilla JS app to test if the integration works. When you click the "Sign In" button, the page should be redirected to a Logto sign-in page, and you should be able to create a new account by entering username and password and complete the sign-in process.

Add Google connector

To add a social connector, go to the "Connector" tab in the Admin Console, then click on "Social connectors". From there, click "Add social connector".

In the openning modal, select "Google" and click "Next".

On the next page, you will see a two-column layout with the README content on the left and configuration on the right.

Feel free to follow the README file in place or read the following section to complete the configuration process. If you follow the in-place guide, you can skip the next section.

Set up Google OAuth app

Set up a project in the Google API Console

• Visit the Google API Console and sign in with your Google account.
• Click the Select a project button on the top menu bar, and click the New Project button to create a project.
• In your newly created project, click the APIs & Services to enter the APIs & Services menu.

Configure your consent screen

• On the left APIs & Services menu, click the OAuth consent screen button.
• Choose the User Type you want, and click the Create button. (Note: If you select External as your User Type, you will need to add test users later.)

Now you will be on the Edit app registration page.

Config OAuth consent screen

• Follow the instructions to fill out the OAuth consent screen form.
• Click SAVE AND CONTINUE to continue.

Config scopes

• Click ADD OR REMOVE SCOPES and select ../auth/userinfo.email, ../auth/userinfo.profile and openid in the popup drawer, and click UPDATE to finish.
• Fill out the form as you need.
• Click SAVE AND CONTINUE to continue.

Add test users (External user type only)

• Click ADD USERS and add test users to allow these users to access your application while testing.
• Click SAVE AND CONTINUE to continue.

Now you should have the Google OAuth 2.0 consent screen configured.

Obtain OAuth 2.0 credentials

• On the left APIs & Services menu, click the Credentials button.
• On the Credentials page, click the + CREATE CREDENTIALS button on the top menu bar, and select OAuth client ID.
• On the Create OAuth client ID page, select Web application as the application type.
• Fill out the basic information for your application.
• Click + Add URI to add an authorized domain to the Authorized JavaScript origins section. This is the domain that your logto authorization page will be served from. In our case, this will be ${your_logto_origin}. e.g.https://logto.dev.
• Click + Add URI in the **Authorized redirect URIs** section to set up the **Authorized redirect URIs**, which redirect the user to the application after logging in. In our case, this will be ${your_logto_endpoint}/callback/${connector_id}. e.g. https://logto.dev/callback/${connector_id}. The connector_id can be found on the top bar of the Logto Admin Console connector details page.
• Click Create to finish and then you will get the Client ID and Client Secret.

References

Config types

Name	Type
clientId	string
clientSecret	string

Google developer docs

Google Identity: Setting up OAuth 2.0

Save your configuration

Double check you have filled out necessary values in the Logto connector configuration area. Click "Save and Done" (or "Save changes") and the Google connector should be available now.

Enable Google connector in Sign-in Experience

Switch to the "Sign-in experience" tab, then click the "Sign-up and sign-in" tab.

note:

If it's the first time you enter the tab, you will see a quick introduction about Sign-in Experience and its basic configuration.

Select "None" for the "Sign-up identifier" to provide minimum sign-up effort for Google sign-in, which may increase your conversion rate.

In the "Social sign-in" section, add "Add Social Connector" and choose "Google". Then you should be able to see a button with text "Continue with Google" in the preview section.

Finally, click "Save changes" on the bottom right corner.

Testing and Validation

Return to your Vanilla JS app. You should now be able to sign in with Google. Enjoy!

Further readings

Protect your API For native and single page apps, you'll need to call one or more API endpoints to retrieve and update data.
Learn more about identifying who's who and keeping your API secure.

User management We know you care about user management and activities, as we also do.
Learn more about how to know your users and see the figures like DAU and MAU graphically.

Localization From one regional business to a global corporate, the willingness to offer the best user experience won't change.
You can change current language phrases or add a new language without friction.

Customer IAM series Our serial blog posts about Customer (or Consumer) Identity and Access Management, from 101 to advanced topics and beyond.