Add examples and doc on how to customize the chain and hardfork

README.md

@@ -29,19 +29,26 @@ const txParams = {
   data: '0x7f7465737432000000000000000000000000000000000000000000000000000000600057',
 }
 
-const tx = new EthereumTx(txParams)
+// The second parameter is not necessary if these values are used
+const tx = new EthereumTx(txParams, { chain: 'mainnet', hardfork: 'petersburg' })
 tx.sign(privateKey)
 const serializedTx = tx.serialize()
 ```
 
 # Chain and Hardfork Support
 
-This library uses the [ethereumjs-common](https://github.com/ethereumjs/ethereumjs-common)
-package to support different chain and hardfork options, see API documentation
-for details.
+The `Transaction` and `FakeTransaction` constructors receives a second parameter that lets you specify the chain and hardfork
+to be used. By default, `mainnet` and `petersburg` will be used.
 
-Currently all hardforks up to `petersburg` are supported, `EIP-155` replay protection
-is activated since the `spuriousDragon` hardfork.
+There are two ways of customizing these. The first one, as shown in the previous section, is by
+using an object with `chain` and `hardfork` names. You can see en example of this in [./examples/ropsten-tx.ts](./examples/ropsten-tx.ts).
+
+The second option is by passing the option `common` set to an instance of [ethereumjs-common](https://github.com/ethereumjs/ethereumjs-common)' Common. This is specially useful for custom networks or chains/hardforks not yet supported by `ethereumjs-common`. You can see en example of this in [./examples/custom-chain-tx.ts](./examples/custom-chain-tx.ts).
+
+# EIP-155 support
+
+`EIP-155` replay protection is activated since the `spuriousDragon` hardfork. To disable it, set the
+hardfork in the `Transaction`'s constructor.
 
 # API
 

examples/custom-chain-tx.ts

@@ -0,0 +1,50 @@
+import { Transaction } from '../src'
+import Common from 'ethereumjs-common'
+import { bufferToHex, privateToAddress } from 'ethereumjs-util'
+
+// In this example we create a transaction for a custom network.
+//
+// All of these network's params are the same than mainnets', except for name, chainId, and
+// networkId, so we use the Common.forCustomChain method.
+const customCommon = Common.forCustomChain(
+  'mainnet',
+  {
+    name: 'my-network',
+    networkId: 123,
+    chainId: 2134,
+  },
+  'petersburg',
+)
+
+// We pass our custom Common object whenever we create a transaction
+
+const tx = new Transaction(
+  {
+    nonce: 0,
+    gasPrice: 100,
+    gasLimit: 1000000000,
+    value: 100000,
+  },
+  { common: customCommon },
+)
+
+// Once we created the transaction using the custom Common object, we can use it as a normal tx.
+
+// Here we sign it and validate its signature
+const privateKey = new Buffer(
+  'e331b6d69882b4cb4ea581d88e0b604039a3de5967688d3dcffdd2270c0fd109',
+  'hex',
+)
+
+tx.sign(privateKey)
+
+if (
+  tx.validate() &&
+  bufferToHex(tx.getSenderAddress()) === bufferToHex(privateToAddress(privateKey))
+) {
+  console.log('Valid signature')
+} else {
+  console.log('Invalid signature')
+}
+
+console.log("The transaction's chain id is", tx.getChainId())

examples/ropsten-tx.ts

@@ -0,0 +1,16 @@
+import { Transaction } from '../src'
+import { bufferToHex } from 'ethereumjs-util'
+
+const tx = new Transaction(
+  '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',
+  { chain: 'ropsten', hardfork: 'petersburg' },
+)
+
+if (
+  tx.validate() &&
+  bufferToHex(tx.getSenderAddress()) === '0x9dfd2d2b2ed960923f7bf2e8883d73f213f3b24b'
+) {
+  console.log('Correctly created the tx')
+} else {
+  console.error('Invalid tx')
+}

examples/transactions.ts

@@ -5,6 +5,7 @@ import { Transaction } from '../src'
 
 // 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 = new Transaction({
   nonce: 0,
   gasPrice: 100,
@@ -49,7 +50,7 @@ const rawTx = [
   '0x5bd428537f05f9830e93792f90ea6a3e2d1ee84952dd96edbae9f658f831ab13',
 ]
 
-const tx2 = new Transaction(rawTx)
+const tx2 = new Transaction(rawTx) // This is also a maninnet transaction
 
 // Note rlp.decode will actually produce an array of buffers `new Transaction` will
 // take either an array of buffers or an array of hex strings.