on(eventName, listener)

Feature	Subscribes to wallet events.
Parameters	string eventName, function listener
Return Value	(void)

example

// Listen for when the user changes their selected account in the wallet
// 'accountsChanged' event occurs also if the permissions of some of the accounts have changed.
provider.on('accountsChanged', (accounts) => {
  if (accounts.length === 0) {
    // All accounts were disconnected
    console.log('User disconnected all accounts.');
  } else {
    // The new array of permitted accounts.
    // accounts[0] is the new selected address.
    console.log('New permitted accounts list:', accounts);
    console.log('New selected address:', accounts[0]);
  }
});

// Listen for when the user fully disconnects the site
provider.on('disconnect', (message) => {
  console.log(message);
});

// Listen for network changes
provider.on('chainChanged', (chainId) => {
  console.log('Network changed to:', chainId);
  // It's recommended to reload the page on chain change
  window.location.reload();
});