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JavaScript / TypeScript

JavaScript is the most popular language for Bitcoin application development, especially for web wallets, browser extensions, and Node.js backend services.

bitcoinjs-lib​

bitcoinjs-lib is the most established Bitcoin library for JavaScript. It handles transaction construction, signing, address generation, and script operations.

Installation​

npm install bitcoinjs-lib ecpair @bitcoinerlab/secp256k1

Generate a SegWit Address​

const bitcoin = require('bitcoinjs-lib');
const ecpair = require('ecpair');
const ecc = require('@bitcoinerlab/secp256k1');

const ECPair = ecpair.ECPairFactory(ecc);

// Generate a random key pair
const keyPair = ECPair.makeRandom();

// Create a P2WPKH (native SegWit) address
const { address } = bitcoin.payments.p2wpkh({
  pubkey: keyPair.publicKey,
  network: bitcoin.networks.testnet,
});

console.log('Address:', address);        // tb1q...
console.log('Private key (WIF):', keyPair.toWIF());

Create and Sign a Transaction​

const bitcoin = require('bitcoinjs-lib');
const ecpair = require('ecpair');
const ecc = require('@bitcoinerlab/secp256k1');

const ECPair = ecpair.ECPairFactory(ecc);
const network = bitcoin.networks.regtest;

// Your key pair (from WIF or generated)
const keyPair = ECPair.fromWIF('your-private-key-wif', network);

const psbt = new bitcoin.Psbt({ network });

// Add input (reference a UTXO you own)
psbt.addInput({
  hash: 'previous-txid-hex',
  index: 0,
  witnessUtxo: {
    script: bitcoin.payments.p2wpkh({
      pubkey: keyPair.publicKey,
      network,
    }).output,
    value: 100000, // satoshis
  },
});

// Add output (where to send)
psbt.addOutput({
  address: 'recipient-address',
  value: 90000, // satoshis (difference is fee)
});

// Sign and finalize
psbt.signInput(0, keyPair);
psbt.finalizeAllInputs();

// Get the raw transaction hex
const rawTx = psbt.extractTransaction().toHex();
console.log('Raw transaction:', rawTx);

HD Wallet with BIP-32/39​

const bitcoin = require('bitcoinjs-lib');
const bip39 = require('bip39');
const { BIP32Factory } = require('bip32');
const ecc = require('@bitcoinerlab/secp256k1');

const bip32 = BIP32Factory(ecc);

// Generate mnemonic
const mnemonic = bip39.generateMnemonic(256); // 24 words
const seed = bip39.mnemonicToSeedSync(mnemonic);

// Derive keys (BIP-84 for native SegWit)
const root = bip32.fromSeed(seed, bitcoin.networks.testnet);
const account = root.derivePath("m/84'/1'/0'");
const firstAddress = account.derive(0).derive(0);

const { address } = bitcoin.payments.p2wpkh({
  pubkey: firstAddress.publicKey,
  network: bitcoin.networks.testnet,
});

console.log('Mnemonic:', mnemonic);
console.log('First address:', address);

BDK for JavaScript​

BDK provides JavaScript/TypeScript bindings via WebAssembly:

npm install @bitcoindevkit/bdk-wasm

BDK handles coin selection, fee estimation, and PSBT construction automatically, making it ideal for production wallet development.

Ecosystem Libraries​

PackagePurpose
bitcoinjs-libCore transaction/address operations
ecpairElliptic curve key pairs
bip32HD key derivation (BIP-32)
bip39Mnemonic seed phrases (BIP-39)
bolt11Lightning invoice encoding/decoding
@scure/btc-signerModern, audited alternative to bitcoinjs-lib