Add authentication to your Vanilla JS application

Vanilla JS: Integrate @logto/browser

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.

Prerequisites

• A Logto Cloud account or a self-hosted Logto.
• A single-page application (SPA) created in Logto Console.
• A vanilla JS app project.

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>

Integration

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.

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.

Checkpoint: Test your application

Now, you can test your application:

1. Run your application, you will see the sign-in button.
2. Click the sign-in button, the SDK will init the sign-in process and redirect you to the Logto sign-in page.
3. After you signed in, you will be redirected back to your application and see user ID and the sign-out button.
4. Click the sign-out button to sign-out.

Get user information

Display user information

To display the user's information, you can use the logtoClient.getIdTokenClaims() method. For example, in your Home page:

Home.js

const userInfo = await logtoClient.getIdTokenClaims();

// Generate display table for ID token claims
const table = document.createElement('table');
const thead = document.createElement('thead');
const tr = document.createElement('tr');
const thName = document.createElement('th');
const thValue = document.createElement('th');
thName.innerHTML = 'Name';
thValue.innerHTML = 'Value';
tr.append(thName, thValue);
thead.append(tr);
table.append(thead);

const tbody = document.createElement('tbody');

for (const [key, value] of Object.entries(userInfo)) {
  const tr = document.createElement('tr');
  const tdName = document.createElement('td');
  const tdValue = document.createElement('td');
  tdName.innerHTML = key;
  tdValue.innerHTML = typeof value === 'string' ? value : JSON.stringify(value);
  tr.append(tdName, tdValue);
  tbody.append(tr);
}

table.append(tbody);

Request additional claims

You may find some user information are missing in the returned object from getIdTokenClaims(). This is because OAuth 2.0 and OpenID Connect (OIDC) are designed to follow the principle of least privilege (PoLP), and Logto is built on top of these standards.

By default, limited claims are returned. If you need more information, you can request additional scopes to access more claims.

info:

A "claim" is an assertion made about a subject; a "scope" is a group of claims. In the current case, a claim is a piece of information about the user.

Here's a non-normative example the scope - claim relationship:

tip:

The "sub" claim means "subject", which is the unique identifier of the user (i.e. user ID).

Logto SDK will always request three scopes: openid, profile, and offline_access.

To request additional scopes, you can configure the Logto configs:

index.js

import LogtoClient, { UserScope } from '@logto/browser';

const logtoClient = new LogtoClient({
  appId: '<your-application-id>',
  endpoint: '<your-logto-endpoint>',
  scopes: [UserScope.Email, UserScope.Phone],
});

Then you can access the additional claims in the return value of logtoClient.getIdTokenClaims():

const claims = await getIdTokenClaims();
// Now you can access additional claims `claims.email`, `claims.phone`, etc.

Claims that need network requests

To prevent bloating the ID token, some claims require network requests to fetch. For example, the custom_data claim is not included in the user object even if it's requested in the scopes. To access these claims, you can use the logtoClient.fetchUserInfo() method:

const userInfo = await logtoClient.fetchUserInfo();
// Now you can access the claim `userInfo.custom_data`

This method will fetch the user information by requesting to the userinfo endpoint. To learn more about the available scopes and claims, see the Scopes and claims section.

Scopes and claims

Logto uses OIDC scopes and claims conventions to define the scopes and claims for retrieving user information from the ID token and OIDC userinfo endpoint. Both of the "scope" and the "claim" are terms from the OAuth 2.0 and OpenID Connect (OIDC) specifications.

Here's the list of supported scopes and the corresponding claims:

openid

Claim name	Type	Description	Needs userinfo?
sub	string	The unique identifier of the user	No

profile

Claim name	Type	Description	Needs userinfo?
name	string	The full name of the user	No
username	string	The username of the user	No
picture	string	URL of the End-User's profile picture. This URL MUST refer to an image file (for example, a PNG, JPEG, or GIF image file), rather than to a Web page containing an image. Note that this URL SHOULD specifically reference a profile photo of the End-User suitable for displaying when describing the End-User, rather than an arbitrary photo taken by the End-User.	No
created_at	number	Time the End-User was created. The time is represented as the number of milliseconds since the Unix epoch (1970-01-01T00:00:00Z).	No
updated_at	number	Time the End-User's information was last updated. The time is represented as the number of milliseconds since the Unix epoch (1970-01-01T00:00:00Z).	No

Other standard claims include family_name, given_name, middle_name, nickname, preferred_username, profile, website, gender, birthdate, zoneinfo, and locale will be also included in the profile scope without the need for requesting the userinfo endpoint. A difference compared to the claims above is that these claims will only be returned when their values are not empty, while the claims above will return null if the values are empty.

note:

Unlike the standard claims, the created_at and updated_at claims are using milliseconds instead of seconds.

email

Claim name	Type	Description	Needs userinfo?
email	string	The email address of the user	No
email_verified	boolean	Whether the email address has been verified	No

phone

Claim name	Type	Description	Needs userinfo?
phone_number	string	The phone number of the user	No
phone_number_verified	boolean	Whether the phone number has been verified	No

address

Please refer to the OpenID Connect Core 1.0 for the details of the address claim.

custom_data

Claim name	Type	Description	Needs userinfo?
custom_data	object	The custom data of the user	Yes

identities

Claim name	Type	Description	Needs userinfo?
identities	object	The linked identities of the user	Yes
sso_identities	array	The linked SSO identities of the user	Yes

urn:logto:scope:organizations

Claim name	Type	Description	Needs userinfo?
organizations	string[]	The organization IDs the user belongs to	No
organization_data	object[]	The organization data the user belongs to	Yes

urn:logto:scope:organization_roles

Claim name	Type	Description	Needs userinfo?
organization_roles	string[]	The organization roles the user belongs to with the format of <organization_id>:<role_name>	No

---

Considering performance and the data size, if "Needs userinfo?" is "Yes", it means the claim will not show up in the ID token, but will be returned in the userinfo endpoint response.

API resources

We recommend to read 🔐 Role-Based Access Control (RBAC) first to understand the basic concepts of Logto RBAC and how to set up API resources properly.

Configure Logto client

Once you have set up the API resources, you can add them when configuring Logto in your app:

index.js

import LogtoClient from '@logto/browser';

const logtoClient = new LogtoClient({
  // ...other configs
  resources: ['https://shopping.your-app.com/api', 'https://store.your-app.com/api'], // Add API resources
});

Each API resource has its own permissions (scopes).

For example, the https://shopping.your-app.com/api resource has the shopping:read and shopping:write permissions, and the https://store.your-app.com/api resource has the store:read and store:write permissions.

To request these permissions, you can add them when configuring Logto in your app:

index.js

import LogtoClient from '@logto/browser';

const logtoClient = new LogtoClient({
// ...other configs
scopes: ['shopping:read', 'shopping:write', 'store:read', 'store:write'],
resources: ['https://shopping.your-app.com/api', 'https://store.your-app.com/api'], // Add API resources
});

You may notice that scopes are defined separately from API resources. This is because Resource Indicators for OAuth 2.0 specifies the final scopes for the request will be the cartesian product of all the scopes at all the target services.

Thus, in the above case, scopes can be simplified from the definition in Logto, both of the API resources can have read and write scopes without the prefix. Then, in the Logto config:

index.js

import LogtoClient, { UserScope } from '@logto/browser';

const logtoClient = new LogtoClient({
// ...other configs
scopes: ['read', 'write'],
resources: ['https://shopping.your-app.com/api', 'https://store.your-app.com/api'],
});

For every API resource, it will request for both read and write scopes.

note:

It is fine to request scopes that are not defined in the API resources. For example, you can request the email scope even if the API resources don't have the email scope available. Unavailable scopes will be safely ignored.

After the successful sign-in, Logto will issue proper scopes to API resources according to the user's roles.

Fetch access token for the API resource

To fetch the access token for a specific API resource, you can use the getAccessToken method:

const accessToken = await logtoClient.getAccessToken('https://store.your-app.com/api');
console.log('Access token', accessToken);

This method will return a JWT access token that can be used to access the API resource when the user has related permissions. If the current cached access token has expired, this method will automatically try to use a refresh token to get a new access token.

Fetch organization tokens

If organization is new to you, please read 🏢 Organizations (Multi-tenancy) to get started.

You need to add UserScope.Organizations scope when configuring the Logto client:

index.js

import LogtoClient, { UserScope } from '@logto/browser';

const logtoClient = new LogtoClient({
// ...other configs
scopes: [UserScope.Organizations],
});

Once the user is signed in, you can fetch the organization token for the user:

index.js

// Get organizationIds from the userInfo

const claims = await logtoClient.getIdTokenClaims();
const organizationIds = claims.organizations;

/**
 * Or from the ID token claims
 *
 * const claims = await logtoClient.getIdTokenClaims();
 * const organizationIds = claims.organizations;
 */

// Get the organization access token
if (organizationIds.length > 0) {
  const organizationId = organizationIds[0];
  const organizationAccessToken = await logtoClient.getOrganizationToken(organizationId);
  console.log('Organization access token', organizationAccessToken);
}

./code/_scopes-and-claims-code.mdx./code/_config-organization-code.mdx

Attach access token to request headers

Put the token in the Authorization field of HTTP headers with the Bearer format (Bearer YOUR_TOKEN), and you are good to go.

note:

The Bearer Token's integration flow may vary based on the framework or requester you are using. Choose your own way to apply the request Authorization header.

Further readings

End-user flows: authentication flows, account flows, and organization flows Configure connectors Protect your API