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Tooling and infrastructure
Build on X Layer

Deploying with Hardhat#

In this tutorial, we explain step-by-step how to create, compile and deploy a simple smart contract on the X Layer testnet using Hardhat.

What is Hardhat#

Hardhat is a development environment to compile, deploy, test, and debug your smart contract.

Setting up the development environment#

Prerequisites:

To install Hardhat, you need to create an npm project by going to an empty folder, running npm init, and following its instructions. You can use another package manager, like yarn, but we recommend you use npm 7 or later, as it makes installing Hardhat plugins simpler.

Once your project is ready, you should run npm install --save-dev hardhat , install Hardhat toolbox npm install @nomicfoundation/hardhat-toolbox . In order to use your local installation of Hardhat, you need to use npx to run it (i.e., npx hardhat).

Creating your contract#

To create the sample project, run npx hardhat in your project folder:

$ npx hardhat
888    888                      888 888               888
888    888                      888 888               888
888    888                      888 888               888
8888888888  8888b.  888d888 .d88888 88888b.   8888b.  888888
888    888     "88b 888P"  d88" 888 888 "88b     "88b 888
888    888 .d888888 888    888  888 888  888 .d888888 888
888    888 888  888 888    Y88b 888 888  888 888  888 Y88b.
888    888 "Y888888 888     "Y88888 888  888 "Y888888  "Y888

đŸ‘· Welcome to Hardhat v2.9.9 đŸ‘·

? What do you want to do? 

❯ Create a JavaScript project
  Create a TypeScript project
  Create an empty hardhat.config.js
  Quit

Compiling your contract#

Next, if you take a look at the contracts/ folder, you will see Lock.sol:

// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;

// Uncomment this line to use console.log
// import "hardhat/console.sol";

contract Lock {
    uint public unlockTime;
    address payable public owner;

    event Withdrawal(uint amount, uint when);

    constructor(uint _unlockTime) payable {
        require(
            block.timestamp < _unlockTime,
            "Unlock time should be in the future"
        );

        unlockTime = _unlockTime;
        owner = payable(msg.sender);
    }

    function withdraw() public {
        // Uncomment this line, and the import of "hardhat/console.sol", to print a log in your terminal
        // console.log("Unlock time is %o and block timestamp is %o", unlockTime, block.timestamp);

        require(block.timestamp >= unlockTime, "You can't withdraw yet");
        require(msg.sender == owner, "You aren't the owner");

        emit Withdrawal(address(this).balance, block.timestamp);

        owner.transfer(address(this).balance);
    }
}

To compile it, simply run npx hardhat compile

Setting configuration file#

In order to connect to the X Layer network, we need to configure the corresponding network. To set up your config, you have to export an object from hardhat.config.js:

module.exports = {
  defaultNetwork: "hardhat",
  networks: {
    hardhat: {
    },
    xlayer: {
      url: "https://testrpc.xlayer.tech",
      accounts: [privateKey1, privateKey2, ...]
    }
  }
}

Deploying your contract#

Next, to deploy the contract, we will use a Hardhat script. Inside the scripts/ folder you will find a file with the following code:

// We require the Hardhat Runtime Environment explicitly here. This is optional
// but useful for running the script in a standalone fashion through `node <script>`.
//
// You can also run a script with `npx hardhat run <script>`. If you do that, Hardhat
// will compile your contracts, add the Hardhat Runtime Environment's members to the
// global scope, and execute the script.
const hre = require("hardhat");

async function main() {
  const currentTimestampInSeconds = Math.round(Date.now() / 1000);
  const unlockTime = currentTimestampInSeconds + 60;

  const lockedAmount = hre.ethers.utils.parseEther("0.001");

  const Lock = await hre.ethers.getContractFactory("Lock");
  const lock = await Lock.deploy(unlockTime, { value: lockedAmount });

  await lock.deployed();

  console.log(
    `Lock with ${ethers.utils.formatEther(
      lockedAmount
    )}ETH and unlock timestamp ${unlockTime} deployed to ${lock.address}`
  );
}

// We recommend this pattern to be able to use async/await everywhere
// and properly handle errors.
main().catch((error) => {
  console.error(error);
  process.exitCode = 1;
});

Now, you can run it using npx hardhat run:

$ npx hardhat run scripts/deploy.js --network XLayer
Lock with 1 ETH deployed to: 0x5FbDB2315678afecb367f032d93F642f64180aa3
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