pwa-auth sample: prompt

This sample shows how to use pwa-auth in credentialmode="prompt", which prompts the user to sign-in with a saved credential

To see this in action:

1. Click Sign In and choose any provider (e.g. Microsoft)
2. Once you're signed in, the browser will prompt you to save your sign-in. Choose Save.
3. Refresh this page
4. Click Sign In again; you'll be prompted to signed-in with your saved credential

Note: credentialmode relies on the new Credential Management APIs, see browser support. Older browsers will fallback to standard OAuth flows.