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Deploying a Contract in the Browser

Deploying a smart contract on OP_NET through a browser leverages the opnet.web3.deployContract() method from the wallet's Web3Provider. This guide walks you through deploying a contract directly using OP_WALLET in a browser environment.

Learn More

For a detailed guide on interacting with OP_WALLET, refer to Interacting with a Browser Wallet that Directly Supports OP_NET.

Steps to Deploy a Contract​

1. Request Public Key and UTXOs​

First, you must fetch the connected wallet's public key and UTXOs to fund the transaction.

import { networks } from "@btc-vision/bitcoin";
import { Address } from "@btc-vision/transaction";

const pubKey = await opnet.getPublicKey();
const account = Address.fromString(pubKey); // Sender's address

const utxos = await provider.utxoManager.getUTXOs({
  address: account.p2tr(networks.regtest), // Sender's address (P2TR)
});
UTXO Management

Ensure you have enough UTXOs to cover the transaction inputs, gas fees, and any additional outputs.

Learn more about UTXO Manager.

2. Fetch the Contract Bytecode​

Retrieve the contract bytecode from a file or define it directly as a hex string.

// Fetch the bytecode from a file and convert it to a Buffer
const bytecodeArrayBuffer = await fetch("contract.wasm").then((res) =>
  res.arrayBuffer()
);
const bytecodeBuffer = Buffer.from(new Uint8Array(bytecodeArrayBuffer));
// OR directly define the bytecode as a hex string
// const bytecodeBuffer = Buffer.from("your-contract-bytecode", "hex");

3. Using opnet.web3.deployContract()​

The deployContract() method simplifies the deployment process by combining UTXO management, bytecode inclusion, and gas calculations.

const deployTx = await opnet.web3.deployContract({
  from: account.p2tr(networks.regtest), // Sender's address (P2TR)
  bytecode: bytecodeBuffer, // Contract bytecode
  utxos, // UTXOs for funding
  feeRate: Number((await provider.gasParameters()).baseGas * 2n), // Gas fee rate (satoshis per byte)
  priorityFee: 5000n, // Priority fee for faster processing
  // calldata: Buffer.from([]), // Optional initialization calldata
  // optionalOutputs: [ // Optional additional outputs
  //   {
  //     address: "optional-address",
  //     value: 1000, // satoshis
  //   },
  // ],
});

Full Example​

import { networks } from "@btc-vision/bitcoin";
import { Address } from "@btc-vision/transaction";
import { JSONRpcProvider } from "opnet";

// Initialize the provider and OP_NET instance
const provider = new JSONRpcProvider(
  "https://regtest.opnet.org",
  networks.regtest
);
const opnet = window.opnet;

if (!opnet || !opnet.web3) {
  throw new Error("OP_WALLET is not available in this browser.");
}

const pubKey = await opnet.getPublicKey();
const account = Address.fromString(pubKey); // Sender's address

const utxos = await provider.utxoManager.getUTXOs({
  address: account.p2tr(networks.regtest), // Sender's address (P2TR)
});
if (!utxos || utxos.length === 0) {
  throw new Error("No UTXOs available.");
}

// Fetch the bytecode from a file and convert it to a Buffer
const bytecodeArrayBuffer = await fetch("contract.wasm").then((res) =>
  res.arrayBuffer()
);
const bytecodeBuffer = Buffer.from(new Uint8Array(bytecodeArrayBuffer));
// OR directly define the bytecode as a hex string
// const bytecodeBuffer = Buffer.from("your-contract-bytecode", "hex");

// Deploy the contract
const deployTx = await opnet.web3.deployContract({
  from: account.p2tr(networks.regtest), // Sender's address (P2TR)
  bytecode: bytecodeBuffer, // Contract bytecode
  utxos, // UTXOs for funding
  feeRate: Number((await provider.gasParameters()).baseGas * 2n), // Gas fee rate (satoshis per byte)
  priorityFee: 5000n, // Priority fee for faster processing
  // calldata: Buffer.from([]), // Optional initialization calldata
  // optionalOutputs: [ // Optional additional outputs
  //   {
  //     address: "optional-address",
  //     value: 1000, // satoshis
  //   },
  // ],
});

console.log("Deployed contract:", deployTx);

Deployment Result​

The deployContract() method returns a DeploymentResult object:

export interface DeploymentResult {
  readonly transaction: [string, string]; // Array of raw transaction strings
  readonly contractAddress: string; // Contract's address
  readonly contractPubKey: string; // Contract's tweaked public key
  readonly p2trAddress: string; // Contract's P2TR address
  readonly utxos: UTXO[]; // Array of new UTXOs after deployment
}

Best Practices​

  • Always verify that the selected UTXOs can cover the transaction's cost, including fees.
  • Avoid deploying directly on mainnet without thorough testing on regtest or testnet.
  • Handle private keys and sensitive information securely in your browser environment.
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