btc_stuff

Bitcoin transaction examples with bitcoinjs-lib

This is a collection of scripts with various aspects of bitcoin tech (mostly scripts) in TypeScript and/or JavaScript.
When dealing with TypeScript files, run npm run build before running them with node <file>, or use ts-node <file>.

(!) Use at your own risk, only use on the mainnet if you are 100% certain it works the way you want or funds can be lost! (!)

Developed mostly using Bitcoin Core v23, some older ones could expect v22 RPCs

Example usage

Note: this example still works for some files, but is subject to change

Requirements: Make sure to have

• a bitcoin node synced and running on the desired network/networks
• bitcoin-cli working
• nodejs and npm installed and working

Clone this repository, cd into it and install npm dependencies.

git clone https://github.com/antonilol/btc_stuff.git
cd btc_stuff
npm install

Choose a script you want to start with. I will use p2sh.js here.

Edit something (optional), for example: change OP_13 to OP_12.

Run it

Most scripts will either output a locking script or an address, in this case it is a locking script, so put this locking script in Bitcoin Core's decodescript rpc.

$ bitcoin-cli -testnet decodescript 935c87
{
  "asm": "OP_ADD 12 OP_EQUAL",
  "type": "nonstandard",
  "p2sh": "2N9h3wvypp2oLaaGfHiDVix5GSeTPMGnhQv",
  "segwit": {
    "asm": "0 a5d2c3f6d91680a99d36ef8ba054a57ab220520f7ebe93ddb56316f85f292315",
    "hex": "0020a5d2c3f6d91680a99d36ef8ba054a57ab220520f7ebe93ddb56316f85f292315",
    "address": "tb1q5hfv8akez6q2n8fka796q49902ezq5s006lf8hd4vvt0shefyv2sw96epz",
    "type": "witness_v0_scripthash",
    "p2sh-segwit": "2NCqyYd7K5K9pj6SiUXV65NV5baZNvtfxPE"
  }
}

We will be using the address next to p2sh: 2N9h3wvypp2oLaaGfHiDVix5GSeTPMGnhQv.

Send some sats to this address, 1000 for example:

$ bitcoin-cli -testnet sendtoaddress 2N9h3wvypp2oLaaGfHiDVix5GSeTPMGnhQv 0.00001000
ae70f2d7625184471c9bbf3dea64febc5b562131f2b7c6ccbf3125d493402ac1

This will give a TXID, look this up on a block explorer to find out where the desired output is.

You need to look for the output index, where the output with this P2SH address is, counting from zero.

(If it is the first output, the output index is 0, if it is the second, it is 1 and so on.)

Now go back to your editor and put the TXID and the output index in.

It will look like this:

const txid = 'ae70f2d7625184471c9bbf3dea64febc5b562131f2b7c6ccbf3125d493402ac1'; // txid hex here
const vout = 1;

We also need to change the input script because we changed the value from 13 to 12.

The script OP_ADD 12 OP_EQUAL expects 2 numbers that add up to 12, i will chose 4 and 8 here.

tx.setInputScript(0, bitcoin.script.compile([
	bitcoin.opcodes.OP_4,
	bitcoin.opcodes.OP_8,
	redeemScript
]));

Some other values need to be set too, like input_sat to how much sats you sent to the address, fee_sat to how much fee you want to pay and put your own receiving address of a wallet over the placeholder tb1qbech32addresshere.

Now by running the script it should create and broadcast your transaction and print its TXID to the console. This TXID can also be looked up in a block explorer. (mempool.space and blockstream.info have a Details button to show advanced details about scripts.)

If you have any questions, found bugs or have an improvement/addition feel free to submit it in either issues, discussions or pull requests.

Network

Almost all scripts by default use testnet. To use another network (for example mainnet):

add

setChain('main'); // Where 'main' can be replaced by 'test', 'signet' or 'regtest'

(setChain may need to be imported from ./btc.js)

and if applicable (not all script use bitcoinjs-lib), change

const network = bitcoin.networks.testnet;

to

const network = bitcoin.networks.bitcoin; // Where bitcoin can be replaced by testnet or regtest.
                                          // For signet, use testnet (they use the same address prefix).