Purpose of the msal-react account selection code

[peksipatongeis]

On the msal-react samples I've noticed this piece of code:

microsoft-authentication-library-for-js/samples/msal-react-samples/typescript-sample/src/index.tsx

Lines 14 to 18 in e983e25

	// Account selection logic is app dependent. Adjust as needed for different use cases.
	const accounts = msalInstance.getAllAccounts();
	if (accounts.length > 0) {
	msalInstance.setActiveAccount(accounts[0]);
	}

I'm wondering what's the purpose of it, I thought active account is always set for logged in users?

[tnorling]

Active account is not set automatically by the library. Account selection can be dependent on your specific scenario and MSAL does not make any assumptions about which user you intend to acquire tokens for. Setting the "active account" is a way for you to tell MSAL that this is the default account it should use for token requests if a different account is not provided on the request.

[peksipatongeis]

Continuing on the msal-react TypeScript sample the following lines have this:

microsoft-authentication-library-for-js/samples/msal-react-samples/typescript-sample/src/index.tsx

Lines 20 to 26 in e983e25

	msalInstance.addEventCallback((event: EventMessage) => {
	if (event.eventType === EventType.LOGIN_SUCCESS && event.payload) {
	const payload = event.payload as AuthenticationResult;
	const account = payload.account;
	msalInstance.setActiveAccount(account);
	}
	});

Isn't it enough to set the active account on successful login? Did some quick local testing (with the localStorage cache option) and the active account seemed to be always already set for consequent page loads.

I wasn't able to figure out a situation where I would have accounts available but none of them was set as active. So I guess what I meant to initially ask is "What is the use case for the L14-L18 code in the example as we will set the active account on succesful logins?"

[peksipatongeis]

Ok, I think I figured it out. That piece of code was necessary prior to msal-browser v2.16.0 when the active account wasn't being cached and had to be re-set on every page load.

microsoft-authentication-library-for-js/lib/msal-browser/docs/accounts.md

Line 74 in e983e25

Note: As of version 2.16.0 the active account is stored in the cache location configured on your `PublicClientApplication` instance. If you are using a previous version the active account is stored in-memory and thus must be reset on every page load.

Note: As of version 2.16.0 the active account is stored in the cache location configured on your PublicClientApplication instance. If you are using a previous version the active account is stored in-memory and thus must be reset on every page load.