MSAL Library

MSAL stands for Microsoft Authentication Library
The Microsoft Authentication Library (MSAL) enables developers to acquire tokens from the Microsoft identity platform.
Once you have a token the user has been authenticated allowing them to access secured web APIs.
It can be used to provide secure access to Microsoft Graph, other Microsoft APIs, third-party web APIs, or your own web API
link - docs.microsoft.com/en-us/azure/active-directory/develop/msal-overview
link - developer.microsoft.com/en-us/identity/blogs/msal-js-2-0-supports-authorization-code-flow-is-now-generally-available/

MSAL - @azure/msal-browser

Released August 2020 and also referred to as MSAL v2.0.
Also known as Microsoft Identity Platform v2.0.
Work and School accounts and Personal accounts (Microsoft account) and Social accounts (Facebook, Google).
Uses OAuth 2.0 with PKCE (and does not support OAuth 2.0 Implicit Flow).

import * as "msal_browser" from "msal-browser" 
const msal_Instance = new msal_browser.PublicClientApplication 

link - npmjs.com/package/@azure/msal-browser

MSAL - @azure/msal

Released May 2019 and also referred to as MSAL v1.0.
Work and School accounts and Personal accounts (Microsoft account) and Social accounts (Facebook, Google).
Uses OAuth 2.0 Implicit Flow.
This package is no longer being updated.
This is exactly the same package as the one below (msal).
The only difference between them, is the name/naming convention.
This package was released a year later than the "msal" package.
This package was not updated regularly because of the small number of downloads, compared to the "msal" package.
link - npmjs.com/package/@azure/msal

MSAL - msal

Released May 2019 and also referred to as MSAL v1.0.
Work and School accounts and Personal accounts (Microsoft account) and Social accounts (Facebook, Google).
Uses OAuth 2.0 Implicit Flow.
This package is no longer being updated.

import * as "msal" from "msal" 
const msal_Instance = new msal.UserAgentApplication 

link - npmjs.com/package/msal
link - docs.microsoft.com/en-us/azure/active-directory/develop/migrate-spa-implicit-to-auth-code#switch-redirect-uris-to-spa-platform
link - docs.microsoft.com/en-us/azure/active-directory/develop/msal-compare-msal-js-and-adal-js
link - youtube.com/watch?v=kf_VMt_Eh0M
link - github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-browser/docs/v1-migration.md

ADAL - adal-vanilla

Released January 2016 and also known as Microsoft Identity Platform v1.0.
The Azure Active Directory Authentication Library for JavaScript (ADAL) .
Work and School accounts (no personal or social accounts).
Uses OAuth 1.0 Implicit Flow.
This package is no longer being updated. The last update was in 2018.
link - npmjs.com/package/adal-vanilla
link - github.com/AzureAD/azure-activedirectory-library-for-js
link - docs.microsoft.com/en-us/azure/active-directory/develop/msal-migration

Other Links

link - github.com/AzureAD/microsoft-authentication-library-for-js/issues/1072
link - docs.microsoft.com/en-us/azure/active-directory/develop/msal-node-migration
link - docs.microsoft.com/en-us/azure/active-directory/develop/scenario-spa-app-registration
link - docs.microsoft.com/en-gb/graph/tutorials/javascript