How to detect MetaMask login

Question

How can we detect when a user signs in to MetaMask after the page has loaded? Is it necessary to resort to polling, or is there an event that a page can listen out for?

Answer 1

Using web3 version 1.0.0, the metamask provider exposes an 'update' event you can listen to on it's publicConfigStore.

web3.currentProvider.publicConfigStore.on('update', callback);

Your callback will be passed an object with 'selectedAddress' and 'networkVersion' whenever those attributes change.

Answer 2

Requesting Accounts access via 'eth_requestAccounts' is not really the best thing you can do because that will keep adding requests in metamask (bad performances) and a bad UX (popup + notifications)

the way to do it is via

const isUnlocked = await window?.ethereum?._metamask.isUnlocked();
console.debug({ isUnlocked });