bitcoin-tx-lib
Version:
A Typescript library for building and signing Bitcoin transactions
142 lines • 5.39 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Transaction = void 0;
const txbase_1 = require("./base/txbase");
const utils_1 = require("./utils");
class Transaction extends txbase_1.BaseTransaction {
/**
* Creates a new Transaction instance.
* @param pairkey The key pair used to sign the transaction inputs.
* @param options Optional transaction parameters (version, locktime, fee, etc.).
*/
constructor(pairkey, options) {
super(pairkey, options);
}
/**
* Signs the transaction.
* Caches the raw transaction data and the version used for txid calculation.
*/
sign() {
this.cachedata.set("txraw", this.build());
this.cachedata.set("txidraw", this.build("txid"));
}
/**
* Returns the transaction ID (txid) as a hex string.
* The txid is the double SHA-256 hash of the stripped raw transaction (no witness data), reversed in byte order.
*
* @throws Error if the transaction is not signed.
* @returns The txid as a hex string.
*/
getTxid() {
if (!this.cachedata.get("txidraw"))
this.sign();
let hexTransaction = this.cachedata.get("txidraw");
if (!hexTransaction)
throw new Error("Transaction not signed, please sign the transaction");
let txid = (0, utils_1.hash256)(hexTransaction).reverse();
return (0, utils_1.bytesToHex)(txid);
}
/**
* Calculates the total weight of the transaction according to BIP 141.
* Weight = (non-witness bytes * 4) + witness bytes.
*
* @throws Error if the transaction is not signed.
* @returns The transaction weight.
*/
weight() {
// docs https://learnmeabitcoin.com/technical/transaction/size/
if (!this.cachedata.get("txraw"))
this.sign();
// witness marker and flag * 1
let witnessMK = 0; // 2 bytes of marker and flag 0x00+0x01 = 2 bytes * 1
if (this.isSegwit())
witnessMK = 2;
let hexTransaction = this.cachedata.get("txraw");
let witnessInputs = this.inputs.filter(this.isSegwitInput);
// witness size * 1
let witnessSize = witnessInputs.reduce((sum, input) => {
let witness = this.buildWitness(input);
return sum + witness.length;
}, 0);
// discount the size of the witness fields and multiply by 4
let transactionSize = hexTransaction.length;
transactionSize = (transactionSize - (witnessSize + witnessMK)) * 4;
transactionSize += (witnessSize + witnessMK); // * 1
return Math.ceil(transactionSize);
}
/**
* Calculates the virtual size (vBytes) of the transaction.
* Defined as weight divided by 4.
*
* @throws Error if the transaction is not signed.
* @returns The transaction virtual size in bytes.
*/
vBytes() {
// docs https://learnmeabitcoin.com/technical/transaction/size/
return Math.ceil(this.weight() / 4);
}
/**
* Deducts the transaction fee from the output(s) according to the fee-paying strategy.
* If only one output exists, deduct the entire fee from it.
* If `whoPayTheFee` is "everyone", split the fee evenly among all outputs.
* If `whoPayTheFee` is an address, deduct the fee from the output matching that address.
*
* @throws Error if the transaction is not signed.
*/
resolveFee() {
var _a, _b;
if (!this.cachedata.get("txraw"))
this.sign();
let satoshis = Math.ceil(this.vBytes() * ((_a = this.fee) !== null && _a !== void 0 ? _a : 1));
if (this.outputs.length == 1) {
this.outputs[0].amount -= satoshis;
return;
}
if (this.whoPayTheFee === "everyone") {
satoshis = Math.ceil(this.vBytes() * ((_b = this.fee) !== null && _b !== void 0 ? _b : 1) / this.outputs.length);
this.outputs.forEach(out => out.amount -= satoshis);
}
for (let i = 0; i < this.outputs.length; i++) {
if (this.outputs[i].address == this.whoPayTheFee) {
this.outputs[i].amount -= satoshis;
break;
}
}
}
/**
* Calculates the total fee in satoshis based on the virtual size and fee rate.
*
* @returns The transaction fee in satoshis.
*/
getFeeSats() {
var _a;
if (this.whoPayTheFee && this.fee)
this.resolveFee();
const feeSats = Math.ceil(this.vBytes() * ((_a = this.fee) !== null && _a !== void 0 ? _a : 1));
return feeSats;
}
/**
* Returns the raw transaction as a hex string.
*
* @throws Error if the transaction is not signed.
* @returns The raw transaction hex string.
*/
getRawHex() {
if (!this.cachedata.get("txraw"))
this.sign();
return (0, utils_1.bytesToHex)(this.cachedata.get("txraw"));
}
/**
* Returns the raw transaction bytes as a Uint8Array.
*
* @throws Error if the transaction is not signed.
* @returns The raw transaction bytes.
*/
getRawBytes() {
if (!this.cachedata.get("txraw"))
this.sign();
return this.cachedata.get("txraw");
}
}
exports.Transaction = Transaction;
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