10

When a user changes to a different account in metamask, is there a way to detect it asynchronously in code?

I currently use

this.web3.eth.getAccounts((err, accs) => {   
  this.account = accs[0];
});  

but when the account is changed, it still picks up the previous one. Refreshing the page is not a way to go. Did anyone face this and has a solution?

  • Unfortunately, the method most people used is polling for changes using setIntervals. The only other option is checking if accounts match before each call. – ReyHaynes Mar 15 '18 at 12:50
12

As suggested by Metamask FAQs this might be an option:

var account = web3.eth.accounts[0];
var accountInterval = setInterval(function() {
  if (web3.eth.accounts[0] !== account) {
    account = web3.eth.accounts[0];
    updateInterface();
  }
}, 100);

edit

In the newer version metamask exposes an events that could be used to detect whether there's an account change as per new doc

window.ethereum.on('accountsChanged', function (accounts) {
  // Time to reload your interface with accounts[0]!
})
| improve this answer | |
  • Unfortunately at the moment, checking in a loop is the only supported method. – DanF Mar 15 '18 at 16:29
  • Be careful though, I had a problem where I was always matching the if condition because the account I get was always lowercase. – Antoine Delia Jul 19 '18 at 14:14
  • I use and suggest to use onFocus event to handle this issue. – Vanja Dev Jul 13 '19 at 18:39
  • Is there a similar solution for the TronLink extension (tronWeb)? – Dmytro Zarezenko May 5 at 12:35
23

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.

| improve this answer | |
  • 3
    Hi Brian, where can I find documentation about the update event? Have searched the web3 1.0 docs. Thanks. – Vindberg Nov 23 '18 at 19:38
  • On the new metamask version the name has changed, now you have to use web3.currentProvider._publicConfigStore.on('update', callback); But this is probably not going to be supported by metamask in the future so i would recomend using window.ethereum events medium.com/metamask/… – Sr.PEDRO Jul 21 at 13:26
16

From the MetaMask docs:

window.ethereum.on('accountsChanged', function (accounts) {
  // Time to reload your interface with accounts[0]!
})

window.ethereum.on('networkChanged', function (networkId) {
  // Time to reload your interface with the new networkId
})

As @Sr.PEDRO has noted, ethereum.publicConfigStore will not work in the future. In fact, it will be removed entirely. See this GitHub comment for details.

You can also prevent MetaMask from automatically reloading web page:

window.onbeforeunload = function() {
  return "Prevent reload"
}

This only applies if you use the window.web3 object injected by MetaMask, which is also scheduled to be removed.

| improve this answer | |
1

You could put in useEffect a listenEvent like below:

useEffect(() => {
    async function listenMMAccount() {
      window.ethereum.on("accountsChanged", async function() {
        // Time to reload your interface with accounts[0]!
        accounts = await web3.eth.getAccounts();
        // accounts = await web3.eth.getAccounts();
        console.log(accounts);
      });
    }
    listenMMAccount();
  }, []);
| improve this answer | |

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