coinselect-b4bcoin

An unspent transaction output (UTXO) selection module for B4Bcoin.

WARNING: Value units are in satoshis, not B4Bcoin.

Algorithms

Module | Algorithm | Re-orders UTXOs? -|-|- require('coinselect-b4bcoin') | Blackjack, with Accumulative fallback | By Descending Value require('coinselect-b4bcoin/accumulative') | Accumulative - accumulates inputs until the target value (+fees) is reached, skipping detrimental inputs | - require('coinselect-b4bcoin/blackjack') | Blackjack - accumulates inputs until the target value (+fees) is matched, does not accumulate inputs that go over the target value (within a threshold) | - require('coinselect-b4bcoin/break') | Break - breaks the input values into equal denominations of output (as provided) | - require('coinselect-b4bcoin/split') | Split - splits the input values evenly between all outputs, any provided output with .value remains unchanged | -

Note: Each algorithm will add a change output if the input - output - fee value difference is over a dust threshold. This is calculated independently by utils.finalize, irrespective of the algorithm chosen, for the purposes of safety.

Pro-tip: if you want to send-all inputs to an output address, coinselect-b4bcoin/split with a partial output (.address defined, no .value) can be used to send-all, while leaving an appropriate amount for the fee.

Example

let coinSelect = require('coinselect-b4bcoin')
let feeRate = 55 // satoshis per byte
let utxos = [
  ...,
  {
    txId: '...',
    vout: 0,
    ...,
    value: 10000
  }
]
let targets = [
  ...,
  {
    address: 'BhppPwZpJHQF7vtnprQgt31fJTwdHfCVMd',
    value: 5000
  }
]

// ...
let { inputs, outputs, fee } = coinSelect(utxos, targets, feeRate)

// the accumulated fee is always returned for analysis
console.log(fee)

// .inputs and .outputs will be undefined if no solution was found
if (!inputs || !outputs) return

let txb = new b4bcoin.TransactionBuilder()

inputs.forEach(input => txb.addInput(input.txId, input.vout))
outputs.forEach(output => {
  // watch out, outputs may have been added that you need to provide
  // an output address/script for
  if (!output.address) {
    output.address = wallet.getChangeAddress()
    wallet.nextChangeAddress()
  }

  txb.addOutput(output.address, output.value)
})

License MIT