Difference between web3.eth.getCoinbase() and web3.eth.getAccounts()[0]

Question

What is the difference between web3.eth.getCoinbase() and web3.eth.getAccounts()[0]. In both cases, I always get the value, which is the currently selected account in Metamask.

Note: The question is relative to a public-facing dApp. i.e. UI that uses web3.js & interacts with a user's crypto wallet Metamask. It is not for local blockchain development.

Answer 1

web3.eth.getCoinbase() returns the account that your mining rewards go to.

web3.eth.getAccounts()[0] returns the first account you created (index 0)

Web3.js doesnt expose this API (probably because from an application level , there aren't strong use cases for it ), but it is possible to set your Coinbase (Etherbase) to any of your accounts using from the geth console

miner.setEtherbase(eth.accounts[n]) //Where n is the index number

Update:

• Metamask doesnt support web3.eth.getCoinbase() as it is a light client

https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client

• The current pattern for dealing with accounts in metamask:

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

you could probably use web3.eth.getAccounts()[] but this will return an array that you still have to parse.

Example Taken from documentation:

web3.eth.accounts
 web3.eth.accounts
// or async
web3.eth.getAccounts(callback(error, result){ ... })
This property is read only and returns a list of accounts the node controls.

Returns
Array - An array of addresses controlled by client.

Example
var accounts = web3.eth.accounts;
console.log(accounts); // ["0x407d73d8a49eeb85d32cf465507dd71d507100c1"] 

References:

• How do you configure geth to use coinbase?
• https://web3js.readthedocs.io/en/1.0/web3-eth.html#getcoinbase
• https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client
• https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md#dizzy-all-async---think-of-metamask-as-a-light-client
• https://github.com/ethereum/wiki/wiki/JavaScript-API#web3ethaccounts

Answer 2

Those two commands will produce the same result.

web3.eth.getCoinbase() is meant to be used to get your primary (first) account.

web3.eth.getAccounts() is meant to be used to interact with all of your accounts. You can specify the first account by adding the [0].

In general, if you are dealing with more than just your first account, you will want to use getAccounts() and access your first account with [0]. However, it is up the the implementer to decide.