Using Hardhat

1. Initialize a Hardhat TypeScript project

Open your terminal and create a new directory for your project, then navigate into it:

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mkdir my-hardhat-project && cd my-hardhat-project

Initialize an npm project:

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npm init -y

Install the necessary packages for Hardhat and TypeScript:

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npm install --save-dev hardhat ts-node typescript @nomiclabs/hardhat-ethers ethers

Start a new Hardhat project with TypeScript:

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npx hardhat init

When prompted, make the following selections:

• Choose "Create a TypeScript project".

• For the .gitignore prompt, select "Yes" (or y).

• For installing the projects dependencies select "Yes" (or y).

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[~/Milo/my-hardhat-project]$ 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

👷 Welcome to Hardhat v2.18.2 👷‍

✔ What do you want to do? · Create a TypeScript project
✔ Hardhat project root: · /Users/Milo/my-hardhat-project
✔ Do you want to add a .gitignore? (Y/n) · y
✔ Do you want to install this sample project's dependencies with npm (@nomicfoundation/hardhat-toolbox)? (Y/n) · y

2. Drafting the Smart Contract

In the contracts directory, delete the sample smart contract Lock.sol and then create a new file named HelloWorld.sol:

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// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract HelloWorld {
    string public greet = "Hello, Milo!";

    function setGreet(string memory _greet) public {
        greet = _greet;
    }

    function getGreet() public view returns (string memory) {
        return greet;
    }
}

3. Configuring Harhdat for Milo

Edit the hardhat.config.ts file to include Milo Testnet settings:

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import "@nomiclabs/hardhat-ethers";

import { HardhatUserConfig } from "hardhat/config";

const config: HardhatUserConfig = {
  networks: {
    Milo: {
      url: "https://sepolia.Milo.network",
      chainId: 919,
      accounts: ["YOUR_PRIVATE_KEY_HERE"] //BE VERY CAREFUL, DO NOT PUSH THIS TO GITHUB
    }
  },
  solidity: "0.8.0",
};

export default config;

Replace YOUR_PRIVATE_KEY_HERE with your Milo Testnet private key.

IMPORTANT: Do not push your hardhat.config.ts file to github nor share your private key with anyone. It is a very common mistake to push your PK to github so make sure that in the .gitignore you add the hardhat.config.ts

4. Compilation

Compile the smart contract:

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npx hardhat compile

5. Deployment

In the scripts directory, create a new file named deploy.ts:

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import { ethers } from "hardhat";

async function main() {
    const HelloWorld = await ethers.getContractFactory("HelloWorld");
    const gasPrice = ethers.utils.parseUnits('10', 'gwei'); // Adjust the '10' as needed
    const gasLimit = 500000; // Adjust this value based on your needs
    const helloWorld = await HelloWorld.deploy({ gasPrice: gasPrice, gasLimit: gasLimit });
    await helloWorld.deployed();
    console.log("HelloWorld deployed to:", helloWorld.address);
}

main()
  .then(() => process.exit(0))
  .catch(error => {
    console.error(error);
    process.exit(1);
  });

If you get any gas related issues you will need to check what's the best gasPrice and gasLimit.

Deploy the smart contract to the Milo Testnet:

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npx hardhat run scripts/deploy.ts --network Milo