Local WEB3.js provider

The local provider works by intercepting calls to eth_sendTransaction and replaces them with calls to sendSignedTransaction after locally signing the transaction.

Usage

The LocalProvider can be used wherever web3 can. It creates an object that wraps the regular web3 object.

To instantiate a LocalProvider you have to provide 2 parameters:

• a string or array of strings containing Ethereum private keys
• another provider (Http, WebSocket or IPS) which will be used to actually communicate with the node

Installation

npm install web3-local-signing-provider

example

const provider = new LocalProvider([
    'fdb2886b1ff5a0e60f9a4684e385aa7b77f064730304143f08ba96ca1a17effa',
    '8d8697970c933b856a02c5c2a9e1ead92b434d6cb724a0635219a1568a4cfd51'
  ],
  new Web3.providers.HttpProvider('http://localhost:8535'))
const web3 = provider.web3

The LocalProvider creates its own web3 object which can be used as in the example above. An alternative is to create another Web3 object and use the LocalProvider as its provider. Like so

const provider = new LocalProvider([
    'fdb2886b1ff5a0e60f9a4684e385aa7b77f064730304143f08ba96ca1a17effa',
    '8d8697970c933b856a02c5c2a9e1ead92b434d6cb724a0635219a1568a4cfd51'
  ],
  new Web3.providers.HttpProvider('http://localhost:8535'))
const web3 = new Web3(provider)

sending transactions

Once instantiated, the LocalProvider Web3 object can be used the same way you would use a web3 object connected to a node with an unlocked account.

const test = async () => {
    try {
      let receipt = await web3.eth.sendTransaction({
        from: '0x0f21f6fb13310ac0e17205840a91da93119efbec',
        to: '0x205161Cec3b55cA9a5997eeaf983B798D5Dc8408',
        gasPrice: 12,
        value: 1e17
      })
      console.log(receipt)
    } catch (err) {
      console.log(err)
    }
  }

Future development

Some features could be added which would be useful:

• [] Disable the TIMEOUTBLOCK and wait forever for a transaction to be mined
• [] Store pending transactions to LocalStorage and check their status on page reload
• [] Make the varible TIMEOUTBLOCK configurable to tune the error message transaction not mined after 50 blocks
• [] Enable subscribing to events using getPastEvents to allow getting events from Infura
• [] Add Hardware Wallet (Ledger, Trezor) signing ability
• [] Use EthGasStation to estimate gas https://ethgasstation.info/json/ethgasAPI.json