transactions.ts

// This files contain examples on how to use this module.
// You can run them with ts-node, as this project is developed in TypeScript.
// Install the dependencies and run `npx ts-node examples/transactions.ts`

import { Transaction } from '../src'
import { toBuffer } from 'ethereumjs-util'

// We create an unsigned transaction.
// Notice we don't set the `to` field because we are creating a new contract.
// This transaction's chain is set to mainnet.
const tx = Transaction.fromTxData({
  nonce: 0,
  gasPrice: 100,
  gasLimit: 1000000000,
  value: 0,
  data:
    '0x7f4e616d65526567000000000000000000000000000000000000000000000000003057307f4e616d6552656700000000000000000000000000000000000000000000000000573360455760415160566000396000f20036602259604556330e0f600f5933ff33560f601e5960003356576000335700604158600035560f602b590033560f60365960003356573360003557600035335700',
})

// We sign the transaction with this private key.
const privateKey = Buffer.from(
  'e331b6d69882b4cb4ea581d88e0b604039a3de5967688d3dcffdd2270c0fd109',
  'hex',
)

const signedTx = tx.sign(privateKey)

// We have a signed transaction.
// Now for it to be fully fundable the account that we signed it with needs to have a certain amount of wei in to.
// To see how much this account needs we can use the getUpfrontCost() method.
const feeCost = signedTx.getUpfrontCost()
console.log('Total Amount of wei needed:' + feeCost.toString())

// Lets serialize the transaction

console.log('---Serialized TX----')
console.log(signedTx.serialize().toString('hex'))
console.log('--------------------')

// Parsing & Validating Transactions
// If you have a transaction that you want to verify you can parse it.
// If you got it directly from the network it will be rlp encoded.
// You can decode it with the rlp module.
// After that you should have something like:
const rawTx = [
  '0x00',
  '0x09184e72a000',
  '0x2710',
  '0x0000000000000000000000000000000000000000',
  '0x00',
  '0x7f7465737432000000000000000000000000000000000000000000000000000000600057',
  '0x1c',
  '0x5e1d3a76fbf824220eafc8c79ad578ad2b67d01b0c2425eb1f1347e8f50882ab',
  '0x5bd428537f05f9830e93792f90ea6a3e2d1ee84952dd96edbae9f658f831ab13',
]

const tx2 = Transaction.fromValuesArray(rawTx.map(toBuffer)) // This is also a maninnet transaction

// Note rlp.decode will produce an array of buffers.
// So assuming that you were able to parse the transaction, we will now get the sender's address.

console.log('Senders Address: ' + tx2.getSenderAddress().toString())

// Cool now we know who sent the tx!
// Let's verify the signature to make sure it was not some poser.

if (tx2.verifySignature()) {
  console.log('Signature Checks out!')
}

// And hopefully it's verified. For the transaction to be totally valid we would
// also need to check the account of the sender and see if they have enough funds.