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Enable authentication options in a Node.js web app by using Azure Active Directory B2C

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This article describes how to enable, customize, and enhance the Azure Active Directory B2C (Azure AD B2C) authentication experience for your Node.js web application.

Before you start, it's important to familiarize yourself with the following articles:

Use a custom domain

By using a custom domain, you can fully brand the authentication URL. From a user perspective, users remain on your domain during the authentication process, rather than being redirected to the Azure AD B2C b2clogin.com domain name.

To remove all references to "b2c" in the URL, you can also replace your B2C tenant name, contoso.onmicrosoft.com, in the authentication request URL with your tenant ID GUID. For example, you can change https://fabrikamb2c.b2clogin.com/contoso.onmicrosoft.com/ to https://account.contosobank.co.uk/<tenant ID GUID>/.

To use a custom domain and your tenant ID in the authentication URL, follow the guidance in Enable custom domains. Under the project root folder, open the .env file. This file contains information about your Azure AD B2C identity provider.

In the .env file, do the following:

  • Replace all instances of tenant-name.b2clogin.com with your custom domain. For example, replace tenant-name.b2clogin.com, to login.contoso.com.
  • Replace all instances of tenant-name.onmicrosoft.com with your tenant ID. For more information, see Use tenant ID.

The following configuration shows the app settings before the change:

#B2C sign up and sign in user flow/policy authority
SIGN_UP_SIGN_IN_POLICY_AUTHORITY=https://contoso.b2clogin.com/contoso.onmicrosoft.com/B2C_1_susi
#B2C password reset user flow/policy authority
RESET_PASSWORD_POLICY_AUTHORITY=https://contoso.b2clogin.com/contoso.onmicrosoft.com/B2C_1_passwordreset
#B2C edit profile user flow/policy authority
EDIT_PROFILE_POLICY_AUTHORITY=https://contoso.b2clogin.com/contoso.onmicrosoft.com/B2C_1_edit
#B2C authority domain
AUTHORITY_DOMAIN=https://contoso.b2clogin.com
#client redirect url
APP_REDIRECT_URI=http://localhost:3000/redirect
#Logout endpoint 
LOGOUT_ENDPOINT=https://contoso.b2clogin.com/contoso.onmicrosoft.com/B2C_1_susi/oauth2/v2.0/logout?post_logout_redirect_uri=http://localhost:3000

The following configuration shows the app settings after the change:

#B2C sign up and sign in user flow/policy authority
SIGN_UP_SIGN_IN_POLICY_AUTHORITY=https://login.contoso.com/12345678-0000-0000-0000-000000000000/B2C_1_susi
#B2C password reset user flow/policy authority
RESET_PASSWORD_POLICY_AUTHORITY=https://login.contoso.com/12345678-0000-0000-0000-000000000000/B2C_1_passwordreset
#B2C edit profile user flow/policy authority
EDIT_PROFILE_POLICY_AUTHORITY=https://login.contoso.com/12345678-0000-0000-0000-000000000000/B2C_1_edit
#B2C authority domain
AUTHORITY_DOMAIN=https://login.contoso.com
#client redirect url
APP_REDIRECT_URI=http://localhost:3000/redirect
#Logout endpoint 
LOGOUT_ENDPOINT=https://login.contoso.com/12345678-0000-0000-0000-000000000000/B2C_1_susi/oauth2/v2.0/logout?post_logout_redirect_uri=http://localhost:3000

Prepopulate the sign-in name

During a sign-in user journey, your app might target a specific user. When an app targets a user, it can specify in the authorization request the login_hint query parameter with the user's sign-in name. Azure AD B2C automatically populates the sign-in name, and the user needs to provide only the password.

To prepopulate the sign-in name, do the following:

  1. If you're using a custom policy, add the required input claim, as described in Set up direct sign-in.
  2. Find the authCodeRequest object, and set loginHint attribute with the login hint.

The following code snippets demonstrate how to pass the sign-in hint parameter. It uses bob@contoso.com as the attribute value.

authCodeRequest.loginHint = "bob@contoso.com"

return confidentialClientApplication.getAuthCodeUrl(authCodeRequest)
        .then((response) => {

Preselect an identity provider

If you configured the sign-in journey for your application to include social accounts, such as Facebook, LinkedIn, or Google, you can specify the domain_hint parameter. This query parameter provides a hint to Azure AD B2C about the social identity provider that should be used for sign-in. For example, if the application specifies domain_hint=facebook.com, the sign-in flow goes directly to the Facebook sign-in page.

To redirect users to an external identity provider, do the following:

  1. Check the domain name of your external identity provider. For more information, see Redirect sign-in to a social provider.
  2. Find the authCodeRequest object, and set domainHint attribute with the corresponding domain hint.

The following code snippets demonstrate how to pass the domain hint parameter. It uses facebook.com as the attribute value.

authCodeRequest.domainHint = "facebook.com"

return confidentialClientApplication.getAuthCodeUrl(authCodeRequest)
        .then((response) => {

Specify the UI language

Language customization in Azure AD B2C allows your user flow to accommodate a variety of languages to suit your customers' needs. For more information, see Language customization.

To set the preferred language, do the following:

  1. Configure language customization.
  2. Find the authCodeRequest object, and set extraQueryParameters attribute with the corresponding ui_locales extra parameter.

The following code snippets demonstrate how to pass the ui_locales parameter. It uses es-es as the attribute value.

authCodeRequest.extraQueryParameters = {"ui_locales" : "es-es"}

return confidentialClientApplication.getAuthCodeUrl(authCodeRequest)
        .then((response) => {

Pass a custom query string parameter

With custom policies, you can pass a custom query string parameter. A good use-case example is when you want to dynamically change the page content.

To pass a custom query string parameter, do the following:

  1. Configure the ContentDefinitionParameters element.
  2. Find the authCodeRequest object, and set extraQueryParameters attribute with the corresponding extra parameter.

The following code snippets demonstrate how to pass the campaignId custom query string parameter. It uses germany-promotion as the attribute value.

authCodeRequest.extraQueryParameters = {"campaignId" : "germany-promotion"}

return confidentialClientApplication.getAuthCodeUrl(authCodeRequest)
        .then((response) => {

Pass an ID token hint

A relying party application can send an inbound JSON Web Token (JWT) as part of the OAuth2 authorization request. The inbound token is a hint about the user or the authorization request. Azure AD B2C validates the token and then extracts the claim.

To include an ID token hint in the authentication request, do the following:

  1. In your custom policy, define an ID token hint technical profile.
  2. Find the authCodeRequest object, and set extraQueryParameters attribute with the corresponding id_token_hint extra parameter.

The following code snippets demonstrate how to define an ID token hint:

authCodeRequest.extraQueryParameters = {"id_token_hint": idToken}

return confidentialClientApplication.getAuthCodeUrl(authCodeRequest)

Configure logging

The MSAL library generates log messages that can help diagnose problems. The app can configure logging. The app can also give you custom control over the level of detail and whether personal and organizational data is logged.

We recommend that you create an MSAL logging callback and provide a way for users to submit logs when they have authentication problems. MSAL provides these levels of logging detail:

  • Error: Something has gone wrong, and an error was generated. This level is used for debugging and identifying problems.
  • Warning: There hasn't necessarily been an error or failure, but the information is intended for diagnostics and pinpointing problems.
  • Info: MSAL logs events that are intended for informational purposes and not necessarily for debugging.
  • Verbose: This is the default level. MSAL logs the full details of library behavior.

By default, the MSAL logger doesn't capture any personal or organizational data. The library gives you the option to enable logging of personal and organizational data if you decide to do so.

To configure logging, in index.js, configure the following keys:

  • logLevel lets you specify the level of logging. Possible values: Error, Warning, Info, and Verbose.
  • piiLoggingEnabled enables the input of personal data. Possible values: true or false.

The following code snippet demonstrates how to configure MSAL logging:

 const confidentialClientConfig = {
    ...
    system: {
        loggerOptions: {
            loggerCallback(loglevel, message, containsPii) {
                console.log(message);
            },
            piiLoggingEnabled: false,
            logLevel: msal.LogLevel.Verbose,
        }
    }
};

Next steps

Learn more about MSAL.js configuration options.