Metamask web3.eth.account[0] is undefined

Question

I am facing some problem with metamask. I ve copied the code below from the metamask documentation to load the web3 but i get always web3.eth.accounts[0] returns undefined when i try to get the account's address even if metamask is connected to ropsten. The same code works with Mist perfectly.

window.addEventListener('load', function() {

    if (typeof web3 !== 'undefined') {
        // Use Mist/MetaMask's provider
        window.web3 = new Web3(web3.currentProvider);
        console.log("Metamask used");
    } else {
        console.log('No web3? You should consider trying MetaMask!')
        // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
        window.web3 = new Web3(new Web3.providers.HttpProvider("https://ropsten.infura.io/token"));
    }

    console.log('test1'+web3.eth.accounts[0]);

});
console.log('test'+web3.eth.accounts[0]);

i get the output of the first log.

this is your code? maybe is a problem of the asynchronous system... Are you using well the callback function :/ ? — Gawey, May 31 '17 at 14:45

Xavier Leprêtre B9lab · Accepted Answer · 2017-05-31T14:54:03.553

11

Metamask does not let you use synchronous functions. Use instead:

web3.eth.getAccounts(function(error, accounts) {
    ...
});

And remove your second log. You only want to do things after you have properly initialised.

edited May 31 '17 at 14:54

answered May 31 '17 at 14:51

Xavier Leprêtre B9lab

7,366
17
32

Thank you but i think it is a loading issue, because after some refresh it returns the address. – Etherkimist May 31 '17 at 14:52
1

don't go first error and not accounts? :/ web3.eth.getBlock(48, function(error, result){ if(!error) console.log(result) else console.error(error); }) – Gawey May 31 '17 at 14:53
Fixed error, accounts. – Xavier Leprêtre B9lab May 31 '17 at 14:54
If after some refresh it works, it is more likely that it works by a quirk of the refresh. It should work at the first go. – Xavier Leprêtre B9lab May 31 '17 at 14:55
@Etherkimist try to define before the Web3 constant o check the callback. – Gawey May 31 '17 at 14:57

score 0 · Answer 2 · answered Jan 17 '22 at 14:37

0

You can also use await for synchronization.

const getAccount = async () => {
  ...
  const accounts = await web3.eth.getAccounts();
  const account = accounts[0];
  return account;
}

answered Jan 17 '22 at 14:37

Ice Griffin

183
1
7

Metamask web3.eth.account[0] is undefined

2 Answers2