The Microsoft Authentication Library for JavaScript enables client-side JavaScript web applications, running in a web browser, to authenticate users using Azure AD for work and school accounts (AAD), Microsoft personal accounts (MSA), and social identity providers like Facebook, Google, LinkedIn, Microsoft accounts, etc. through Azure AD B2C service.
Msal.js library can be found here: https://github.com/AzureAD/microsoft-authentication-library-for-js
Official Documentation by Microsoft can be found here: https://learn.microsoft.com/en-us/azure/active-directory/develop/msal-overview