Metamask / Mist / Parity Support

As you mention in the readme, this library intends to include:

Complete functionality for all your Ethereum needs

If this is the case, one very common use case is have support Metamask (and even Mist / Parity). Is this feature on the roadmap? If not, is it worth attempting to implement?

As far as I know, it seems like it shouldn’t be too complicated, but obviously we don’t want to include web3 as a dependency, so we should somehow interact with the injected web3.currentProvider directly; https://github.com/MetaMask/faq/blob/master/DEVELOPERS.md

[ricmoo]

This should be good to go now. See https://github.com/ethers-io/ethers.js/commit/67bb0b7f93eee4c435555bcc3fe5eeda6614afc1.

Here is a modified version of the Metamask documentation for you to use ethers.js instead of using web3.

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

  // Checking if Web3 has been injected by the browser (Mist/MetaMask/EthersWallet)
  if (typeof web3 !== 'undefined') {
    // Use Mist/MetaMask's provider
    provider = new ethers.providers.Web3Provider(web3.currentProvider);
    signer = provider.getSigner();
  } else {
    console.log('No web3? You should consider trying MetaMask!')
    // Allow read-only access to the blockchain if no Mist/Metamask/EthersWallet
    provider = ethers.providers.getDefaultProvider();
  }

  // Now you can start your app & access the ethers provider and signer freely:
  startApp()
})

[ricmoo]

The reasons to use BN are:

1. It is already required by the elliptic curve libraries, so rather than using multiple Big Number libraries, we consolidate on the one that would be far too difficult and dangerous to remove
2. BigNumber.js used in web3 is not actually BigNumber.js, but a fork of it, with several changes, and is not actively maintained and does not get bug fixes
3. BigNumber is a decimal library, not an integer library, so it does not accurately reflect the operations required in Ethereum and its use can disregard underflow

The custom signer should instead of overriding sign, could instead override sendTransaction, which would give you the opportunity to intercept signing. This is how ethers.io creates a custom signer as well as the ethers-cli TestRPC wrappers. I haven’t had time to get a simple Custom Signer for MetaMask together, but I will try this week. The ethjs library is a thin wrapper around several ethers.js functions and cut and paste of some web3 functions. The easiest way to do what you wish is to extend the JsonRpcProvider, and override the send function to pass the calls off to the web3.sendAsync instead of call make a request to the network.

Sorry, I have 4 projects I’m trying to catch up on (ethers.js, the firefly hardware wallet, Ethers Wallet and ethers.io) but am hoping to get at least a cookbook entry this week on how to create a custom signer that bridges into Metamask. We certainly need to add more hours in a day… 😃